Chapter 8: NTSC, PAL, and SECAM Overview - deetc

Chapter 8
NTSC, PAL, and
SECAM Overview
To fully understand the NTSC, PAL, and
SECAM encoding and decoding processes, it
is helpful to review the background of these
standards and how they came about.
NTSC Overview
The first color television system was developed
in the United States, and on December 17,
1953, the Federal Communications Commission
(FCC) approved the transmission standard,
with broadcasting approved to begin
January 23, 1954. Most of the work for developing
a color transmission standard that was
compatible with the (then current) 525-line, 60field-per-second,
2:1 interlaced monochrome
standard was done by the National Television
System Committee (NTSC).
Luminance Information
The monochrome luminance (Y) signal is
derived from gamma-corrected red, green, and
blue (R´G´B´) signals:
Y = 0.299R´ + 0.587G´ + 0.114B´
NTSC Overview 247
Due to the sound subcarrier at 4.5 MHz, a
requirement was made that the color signal fit
within the same bandwidth as the monochrome
video signal (0–4.2 MHz).
For economic reasons, another requirement
was made that monochrome receivers
must be able to display the black and white
portion of a color broadcast and that color
receivers must be able to display a monochrome
broadcast.
Color Information
The eye is most sensitive to spatial and temporal
variations in luminance; therefore, luminance
information was still allowed the entire
bandwidth available (0–4.2 MHz). Color information,
to which the eye is less sensitive and
therefore requires less bandwidth, is represented
as hue and saturation information.
The hue and saturation information is
transmitted using a 3.58-MHz subcarrier,
encoded so that the receiver can separate the
hue, saturation, and luminance information
and convert them back to RGB signals for display.
Although this allows the transmission of
color signals within the same bandwidth as
247

248 Chapter 8: NTSC, PAL, and SECAM Overview
monochrome signals, the problem still
remains as to how to cost-effectively separate
the color and luminance information, since
they occupy the same portion of the frequency
spectrum.
To transmit color information, U and V or I
and Q “color difference” signals are used:
R´ –Y = 0.701R´ –0.587G´–0.114B´
B´–Y=–0.299R´–0.587G´ + 0.886B´
U = 0.492(B´ –Y)
V = 0.877(R´ –Y)
I = 0.596R´–0.275G´ –0.321B´
=Vcos33° – Usin 33°
= 0.736(R´–Y) – 0.268(B´ –Y)
Q = 0.212R´–0.523G´ + 0.311B´
=Vsin33° +Ucos33°
= 0.478(R´–Y) + 0.413(B´ –Y)
The scaling factors to generate U and V
from (B´ –Y) and (R´ –Y) were derived due to
overmodulation considerations during transmission.
If the full range of (B´ –Y) and (R´ –
Y) were used, the modulated chrominance levels
would exceed what the monochrome transmitters
were capable of supporting.
Experimentation determined that modulated
subcarrier amplitudes of 20% of the Y signal
amplitude could be permitted above white and
below black. The scaling factors were then
selected so that the maximum level of 75%
color would be at the white level.
I and Q were initially selected since they
more closely related to the variation of color
acuity than U and V. The color response of the
eye decreases as the size of viewed objects
decreases. Small objects, occupying frequencies
of 1.3–2.0 MHz, provide little color sensation.
Medium objects, occupying the 0.6–1.3
MHz frequency range, are acceptable if reproduced
along the orange-cyan axis. Larger
objects, occupying the 0–0.6 MHz frequency
range, require full three-color reproduction.
The I and Q bandwidths were chosen
accordingly, and the preferred color reproduction
axis was obtained by rotating the U and V
axes by 33°. The Q component, representing
the green-purple color axis, was band-limited
to about 0.6 MHz. The I component, representingtheorange-cyancoloraxis,wasband-limited
to about 1.3 MHz.
Another advantage of limiting the I and Q
bandwidths to 1.3 MHz and 0.6 MHz, respectively,
is to minimize crosstalk due to asymmetrical
sidebands as a result of lowpass filtering
the composite video signal to about 4.2 MHz.
Q is a double sideband signal; however, I is
asymmetrical, bringing up the possibility of
crosstalk between I and Q. The symmetry of Q
avoids crosstalk into I; since Q is bandwidth
limited to 0.6 MHz, I crosstalk falls outside the
Qbandwidth.
Advances in electronics have prompted
changes. U and V, both bandwidth-limited to
1.3 MHz, are now commonly used instead of I
and Q. A greater amount of processing is
required in the decoder due to both U and V
being asymmetrical about the color subcarrier.
The UV and IQ vector diagram is shown in
Figure 8.1.
Color Modulation
I and Q (or U and V) are used to modulate a
3.58-MHz color subcarrier using two balanced
modulators operating in phase quadrature: one
modulator is driven by the subcarrier at sine
phase, the other modulator is driven by the
subcarrier at cosine phase. The outputs of the
modulators are added together to form the
modulated chrominance signal:

C=Qsin(ωt +33°) +Icos(ωt +33°)
ω =2πF SC
F SC = 3.579545 MHz (± 10 Hz)
or, if U and V are used instead of I and Q:
C=Usinωt+Vcosωt
Hue information is conveyed by the
chrominance phase relative to the subcarrier.
Saturation information is conveyed by chrominance
amplitude. In addition, if an object has
no color (such as a white, gray, or black
object), the subcarrier is suppressed.
YELLOW
167˚
BURST
180˚
62
GREEN
241˚
RED
103˚
88
+ V
90˚
100
80
60
40
20
82 88
Composite Video Generation
CYAN
283˚
IRE SCALE UNITS
82
MAGENTA
61˚
62
– I
303˚
+ Q
33˚
BLUE
347˚
NTSC Overview 249
The modulated chrominance is added to the
luminance information along with appropriate
horizontal and vertical sync signals, blanking
information, and color burst information, to
generate the composite color video waveform
shown in Figure 8.2.
composite NTSC = Y + Q sin (ωt +33°)
+Icos(ωt+33°) +timing
or, if U and V are used instead of I and Q:
composite NTSC = Y + U sin ωt
+Vcosωt +timing
Figure 8.1. UV and IQ Vector Diagram for 75% Color Bars.
+ U
0˚

250 Chapter 8: NTSC, PAL, and SECAM Overview
100 IRE
40 IRE
20 IRE
20 IRE
7.5 IRE
3.58 MHZ
COLOR BURST
(9 ± 1 CYCLES)
WHITE
BLANK LEVEL
YELLOW
LUMINANCE LEVEL
CYAN
GREEN
MAGENTA
RED
BLUE
PHASE = HUE
BLACK
WHITE LEVEL
BLACK LEVEL
BLANK LEVEL
SYNC LEVEL
Figure 8.2. (M) NTSC Composite Video Signal for 75% Color Bars.
COLOR
SATURATION

The bandwidth of the resulting composite
video signal is shown in Figure 8.3.
The I and Q (or U and V) information can
be transmitted without loss of identity as long
as the proper color subcarrier phase relationship
is maintained at the encoding and decoding
process. A color burst signal, consisting of
nine cycles of the subcarrier frequency at a
specific phase, follows most horizontal sync
pulses, and provides the decoder a reference
signalsoastobeabletoproperlyrecovertheI
andQ(orUandV)signals.Thecolorburst
phase is defined to be along the –U axisas
shown in Figure 8.1.
Color Subcarrier Frequency
The specific choice for the color subcarrier frequency
was dictated by several factors. The
first was the need to provide horizontal interlace
to reduce the visibility of the subcarrier,
requiring that the subcarrier frequency, F SC ,
be an odd multiple of one-half the horizontal
line rate. The second factor was selection of a
frequency high enough that it generated a fine
interference pattern having low visibility.
Third, double sidebands for I and Q (or U and
V) bandwidths below 0.6 MHz had to be
allowed.
Thechoiceofthefrequenciesis:
FH =(4.5x10 6 /286) Hz = 15,734.27 Hz
FV =FH /(525/2) = 59.94 Hz
FSC =((13x7x5)/2)xFH = (455/2) x FH = 3.579545 MHz
The resulting F V (field) and F H (line) rates
were slightly different from the monochrome
standards, but fell well within the tolerance
ranges and were therefore acceptable. Figure
8.4 illustrates the resulting spectral interleaving.
NTSC Overview 251
The luminance (Y) components are modulated
due to the horizontal blanking process,
resulting in bunches of luminance information
spaced at intervals of F H . These signals are further
modulated by the vertical blanking process,
resulting in luminance frequency
components occurring at NF H ± MF V .Nhasa
maximum value of about 277 with a 4.2-MHz
bandwidth-limited luminance. Thus, luminance
information is limited to areas about integral
harmonics of the line frequency (F H ), with
additional spectral lines offset from NF H by the
29.97-Hz vertical frame rate.
The area in the spectrum between luminance
groups, occurring at odd multiples of
one-half the line frequency, contains minimal
spectral energy and is therefore used for the
transmission of chrominance information. The
harmonics of the color subcarrier are separated
from each other by F H sincetheyareodd
multiples of one-half F H , providing a half-line
offset and resulting in an interlace pattern that
moves upward. Four complete fields are
required to repeat a specific sample position,
as shown in Figure 8.5.
NTSC Variations
There are three common variations of NTSC,
as shown in Figures 8.6 and 8.7.
The first, called “NTSC 4.43”, iscommonly
used for multistandard analog VCRs. The horizontal
and vertical timing is the same as (M)
NTSC; color encoding uses the PAL modulation
format and a 4.43361875 MHz color subcarrier
frequency.
The second, “NTSC–J”, isusedinJapan.It
isthesameas(M)NTSC,exceptthereisno
blanking pedestal during active video. Thus,
active video has a nominal amplitude of 714
mV.

252 Chapter 8: NTSC, PAL, and SECAM Overview
AMPLITUDE
Y I I Q
I
Q
0.0 1.0
2.0 3.0 3.58 4.2
AMPLITUDE
0.0
Y U
V
CHROMINANCE
SUBCARRIER
(A)
CHROMINANCE
SUBCARRIER
U
V
1.0 2.0 3.0 3.58 4.2
(B)
FREQUENCY (MHZ)
FREQUENCY (MHZ)
Figure 8.3. Video Bandwidths of Baseband (M) NTSC Video. (a)
Using 1.3-MHz I and 0.6-MHz Q signals. (b) Using 1.3-MHz U and
V signals.

Y
I, Q
FH / 2 FH / 2
FH
Y
I, Q
Y I, Q Y I, Q Y
227FH 228FH 229FH
227.5FH 228.5FH
15.734
KHZ
Y
F
29.97 HZ
SPACING
Figure 8.4. Luma and Chroma Frequency Interleave Principle.
Note that 227.5F H =F SC.
F
NTSC Overview 253

254 Chapter 8: NTSC, PAL, and SECAM Overview
ANALOG
FIELD 1
523 524 525 1 2 3 4 5 6 7 8 9 10 22
EQUALIZING
PULSES
ANALOG
FIELD 2
261 262 263 264 265 266 267 268 269 270 271 272 285 286
ANALOG
FIELD 3
523 524 525 1 2 3 4 5 6 7 8 9 10 22
ANALOG
FIELD 4
BURST BEGINS WITH POSITIVE HALF-CYCLE
BURST PHASE = 180˚ RELATIVE TO U
BURST BEGINS WITH NEGATIVE HALF-CYCLE
BURST PHASE = 180˚ RELATIVE TO U
START
OF
VSYNC
SERRATION
PULSES
BURST PHASE
BURST PHASE
EQUALIZING
PULSES
261 262 263 264 265 266 267 268 269 270 271 272 285 286
H / 2 H / 2
HSYNC HSYNC / 2
H / 2 H / 2
Figure 8.5. Four-field (M) NTSC Sequence and Burst Blanking.

"M"
LINE / FIELD = 525 / 59.94
FH = 15.734 KHZ
FV = 59.94 HZ
FSC = 3.579545 MHZ
BLANKING SETUP = 7.5 IRE
VIDEO BANDWIDTH = 4.2 MHZ
AUDIO CARRIER = 4.5 MHZ
CHANNEL BANDWIDTH = 6 MHZ
QUADRATURE MODULATED SUBCARRIER
PHASE = HUE
AMPLITUDE = SATURATION
LINE / FIELD = 525 / 59.94
FH = 15.734 KHZ
FV = 59.94 HZ
FSC = 3.579545 MHZ
The third, called “noninterlaced NTSC,” is
a 262-line, 60 frames-per-second version of
NTSC, as shown in Figure 8.7. This format is
identical to standard (M) NTSC, except that
there are 262 lines per frame.
RF Modulation
Figures 8.8, 8.9, and 8.10 illustrate the basic
process of converting baseband (M) NTSC
composite video to a RF (radio frequency) signal.
Figure 8.8a shows the frequency spectrum
of a baseband composite video signal. It is similar
to Figure 8.3, however, Figure 8.3 only
shows the upper sideband for simplicity. The
“video carrier” notation at 0 MHz serves only
as a reference point for comparison with Figure
8.8b.
Figure 8.8b shows the audio/video signal
as it resides within a 6-MHz channel (such as
channel 3). The video signal has been lowpass
"NTSC–J"
BLANKING SETUP = 0 IRE
VIDEO BANDWIDTH = 4.2 MHZ
AUDIO CARRIER = 4.5 MHZ
CHANNEL BANDWIDTH = 6 MHZ
Figure 8.6. Common NTSC Systems.
"NTSC 4.43"
LINE / FIELD = 525 / 59.94
FH = 15.734 KHZ
FV = 59.94 HZ
FSC = 4.43361875 MHZ
BLANKING SETUP = 7.5 IRE
VIDEO BANDWIDTH = 4.2 MHZ
AUDIO CARRIER = 4.5 MHZ
CHANNEL BANDWIDTH = 6 MHZ
NTSC Overview 255
filtered, most of the lower sideband has been
removed, and audio information has been
added.
Figure 8.8c details the information present
on the audio subcarrier for stereo (BTSC)
operation.
As shown in Figures 8.9 and 8.10, back
porch clamping of the analog video signal
ensures that the back porch level is constant,
regardless of changes in the average picture
level. White clipping of the video signal prevents
the modulated signal from going below
10%; below 10% may result in overmodulation
and “buzzing” in television receivers. The
video signal is then lowpass filtered to 4.2 MHz
and drives the AM (amplitude modulation)
video modulator. The sync level corresponds
to 100% modulation, the blanking corresponds
to 75%, and the white level corresponds to 10%.
(M) NTSC systems use an IF (intermediate
frequency) for the video of 45.75 MHz.

256 Chapter 8: NTSC, PAL, and SECAM Overview
START
OF
VSYNC
261 262 1 2 3 4 5 6 7 8 9 10 22
At this point, audio information is added on
a subcarrier at 41.25 MHz. A monaural audio
signal is processed as shown in Figure 8.9 and
drives the FM (frequency modulation) modulator.
The output of the FM modulator is added
to the IF video signal.
The SAW filter, used as a vestigial sideband
filter, provides filtering of the IF signal.
The mixer, or up converter, mixes the IF signal
with the desired broadcast frequency. Both
sum and difference frequencies are generated
by the mixing process, so the difference signal
is extracted by using a bandpass filter.
Stereo Audio (Analog)
BTSC
The implementation of stereo audio, known as
the BTSC system (Broadcast Television Systems
Committee), is shown in Figure 8.10.
Countries that use this system include the
United States, Canada, Mexico, Brazil, and Taiwan.
BURST BEGINS WITH POSITIVE HALF-CYCLE
BURST PHASE = REFERENCE PHASE = 180˚ RELATIVE TO U
BURST BEGINS WITH NEGATIVE HALF-CYCLE
BURST PHASE = REFERENCE PHASE = 180˚ RELATIVE TO U
Figure 8.7. Noninterlaced NTSC Frame Sequence.
To enable stereo, L–R information is transmitted
using a suppressed AM subcarrier. A
SAP (secondary audio program) channel may
also be present, commonly used to transmit a
second language or commentary. A professional
channel may be present, allowing communication
with remote equipment and
people.
Zweiton M
This implementation for analog stereo audio
(ITU-R BS.707) is similar to that used for PAL.
The L+R information is transmitted on a FM
subcarrier at 4.5 MHz. The R information is
transmitted on a second FM subcarrier at (4.5
MHz + 15.5F H )or4.72MHz.Thissystemis
used in South Korea.
EIA-J
This implementation for analog stereo audio is
similartoBTSC,andisusedinJapan.TheL–R
signal, or a second L+R signal, is transmitted
on a second FM subcarrier.

–4.5
CHROMINANCE
SUBCARRIER
–4.2
–3.58
VIDEO
CARRIER
CHROMINANCE
SUBCARRIER
–3.0 –1.0 0.0 1.0
3.0 3.58 4.2 4.5
VIDEO
CARRIER
–4.0 –3.0 –0.75 0.0 1.0
3.0 3.58 4.2 4.5 5.0
AUDIO
CARRIER
0.0
L + R
(FM)
0.75 MHZ
VESTIGIAL
SIDEBAND
STEREO
PILOT
–1.25
L – R
(AM)
FH = 15,734 HZ
(A)
6 MHZ CHANNEL
(B)
(C)
CHROMINANCE
SUBCARRIER
SAP
(FM)
AUDIO
CARRIER
FH 2 FH 3 FH 4 FH 5 FH 6.5 FH
4.75
PROFESSIONAL
CHANNEL (FM)
NTSC Overview 257
FREQUENCY (MHZ)
FREQUENCY (MHZ)
FREQUENCY
Figure 8.8. Transmission Channel for (M) NTSC. (a) Frequency spectrum of baseband composite
video. (b) Frequency spectrum of typical channel including audio information. (c) Detailed
frequency spectrum of BTSC stereo audio information.

258 Chapter 8: NTSC, PAL, and SECAM Overview
Analog Channel Assignments
Tables 8.1 through 8.4 list the typical channel
assignments for VHF, UHF, and cable for various
NTSC systems.
Note that cable systems routinely reassign
channel numbers to alternate frequencies to
minimize interference and provide multiple
levels of programming (such as two versions of
a premium movie channel: one for subscribers,
and one for nonsubscribers during pre-view
times).
AUDIO LEFT
AUDIO RIGHT
(M) NTSC
COMPOSITE
VIDEO
5 KHZ
CLOCK
BACK
PORCH
CLAMP
AND
WHITE
LEVEL
CLIP
L + R
---------------
75 µS
PRE-EMPHASIS
---------------
50–15000 HZ BPF
PLL
PLL
PLL
4.2 MHZ
LPF
45.75 MHZ
IF VIDEO CARRIER
41.25 MHZ
IF AUDIO CARRIER
AM
MODULATOR
VIDEO CARRIER
OF DESIRED CHANNEL
FM
MODULATOR
+
Use by Country
Figure 8.6 shows the common designations for
NTSC systems. The letter “M” refers to the
monochrome standard for line and field rates
(525/59.94), a video bandwidth of 4.2 MHz, an
audio carrier frequency 4.5 MHz above the
video carrier frequency, and a RF channel
bandwidth of 6 MHz. The “NTSC” refers to the
technique to add color information to the
monochrome signal. Detailed timing parameters
can be found in Table 8.9.
SAW
FILTER
41–47 MHZ
BANDWIDTH
MIXER
(UP CONVERTER)
BANDPASS
FILTER
Figure 8.9. Typical RF Modulation Implementation for (M) NTSC: Mono Audio.
MODULATED RF
AUDIO / VIDEO
(6 MHZ BANDWIDTH)

AUDIO LEFT
AUDIO RIGHT
(M) NTSC
COMPOSITE
VIDEO
PROFESSIONAL
CHANNEL
AUDIO
SECONDARY
AUDIO
BACK
PORCH
CLAMP
AND
WHITE
LEVEL
CLIP
150 µS
PRE-EMPHASIS
---------------
300–3,400 HZ BPF
PROFESSIONAL CHANNEL
50–10,000 HZ BPF
---------------
BTSC
COMPRESSION
SECONDARY AUDIO PROGRAM (SAP)
FM STEREO
PILOT SIGNAL
L – R
---------------
50–15,000 HZ BPF
---------------
BTSC
COMPRESSION
L + R
---------------
75 µS
PRE-EMPHASIS
---------------
50–15,000 HZ BPF
4.2 MHZ
LPF
41.25 MHZ – FH
AM
MODULATOR
45.75 MHZ
IF VIDEO CARRIER
FM
MODULATOR
41.25 MHZ – 6.5FH
IF AUDIO CARRIER
FM
MODULATOR
41.25 MHZ – 5FH
IF AUDIO CARRIER
STEREO
MODULATOR
+
SAW
FILTER
41–47 MHZ
BANDWIDTH
+
+
+
MIXER
(UP CONVERTER)
CHANNEL
SELECT
NTSC Overview 259
BANDPASS
FILTER
MODULATED RF
AUDIO / VIDEO
Figure 8.10. Typical RF Modulation Implementation for (M) NTSC: BTSC Stereo Audio.

260 Chapter 8: NTSC, PAL, and SECAM Overview
Table 8.1. Analog Broadcast Nominal Frequencies for North and South America.
Broadcast
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
Broadcast
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
–
–
2
3
4
5
6
7
8
9
–
–
55.25
61.25
67.25
77.25
83.25
175.25
181.25
187.25
–
–
59.75
65.75
71.75
81.75
87.75
179.75
185.75
191.75
–
–
54–60
60–66
66–72
76–82
82–88
174–180
180–186
186–192
40
41
42
43
44
45
46
47
48
49
627.25
633.25
639.25
645.25
651.25
657.25
663.25
669.25
675.25
681.25
631.75
637.75
643.75
649.75
655.75
661.75
667.75
673.75
679.75
685.75
626–632
632–638
638–644
644–650
650–656
656–662
662–668
668–674
674–680
680–686
10
11
12
13
14
15
16
17
18
19
193.25
199.25
205.25
211.25
471.25
477.25
483.25
489.25
495.25
501.25
197.75
203.75
209.75
215.75
475.75
481.75
487.75
493.75
499.75
505.75
192–198
198–204
204–210
210–216
470–476
476–482
482–488
488–494
494–500
500–506
50
51
52
53
54
55
56
57
58
59
687.25
693.25
699.25
705.25
711.25
717.25
723.25
729.25
735.25
741.25
691.75
697.75
703.75
709.75
715.75
721.75
727.75
733.75
739.75
745.75
686–692
692–698
698–704
704–710
710–716
716–722
722–728
728–734
734–740
740–746
20
21
22
23
24
25
26
27
28
29
507.25
513.25
519.25
525.25
531.25
537.25
543.25
549.25
555.25
561.25
511.75
517.75
523.75
529.75
535.75
541.75
547.75
553.75
559.75
565.75
506–512
512–518
518–524
524–530
530–536
536–542
542–548
548–554
554–560
560–566
60
61
62
63
64
65
66
67
68
69
747.25
753.25
759.25
765.25
771.25
777.25
783.25
789.25
795.25
801.25
751.75
757.75
763.75
769.75
775.75
781.75
787.75
793.75
799.75
805.75
746–752
752–758
758–764
764–770
770–776
776–782
782–788
788–794
794–800
800–806
30
31
32
33
34
35
36
37
38
39
567.25
573.25
579.25
585.25
591.25
597.25
603.25
609.25
615.25
621.25
571.75
577.75
583.75
589.75
595.75
601.75
607.75
613.75
619.75
625.75
566–572
572–578
578–584
584–590
590–596
596–602
602–608
608–614
614–620
620–626

NTSC Overview 261
Table 8.2. Analog Broadcast Nominal Frequencies for Japan.
Broadcast
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
Broadcast
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
–
1
2
3
4
5
6
7
8
9
–
91.25
97.25
103.25
171.25
177.25
183.25
189.25
193.25
199.25
–
95.75
101.75
107.75
175.75
181.75
187.75
193.75
197.75
203.75
–
90–96
96–102
102–108
170–176
176–182
182–188
188–194
192–198
198–204
40
41
42
43
44
45
46
47
48
49
633.25
639.25
645.25
651.25
657.25
663.25
669.25
675.25
681.25
687.25
637.75
643.75
649.75
655.75
661.75
667.75
673.75
679.75
685.75
691.75
632–638
638–644
644–650
650–656
656–662
662–668
668–674
674–680
680–686
686–692
10
11
12
13
14
15
16
17
18
19
205.25
211.25
217.25
471.25
477.25
483.25
489.25
495.25
501.25
507.25
209.75
215.75
221.75
475.75
481.75
487.75
493.75
499.75
505.75
511.75
204–210
210–216
216–222
470–476
476–482
482–488
488–494
494–500
500–506
506–512
50
51
52
53
54
55
56
57
58
59
693.25
699.25
705.25
711.25
717.25
723.25
729.25
735.25
741.25
747.25
697.75
703.75
709.75
715.75
721.75
727.75
733.75
739.75
745.75
751.75
692–698
698–704
704–710
710–716
716–722
722–728
728–734
734–740
740–746
746–752
20
21
22
23
24
25
26
27
28
29
513.25
519.25
525.25
531.25
537.25
543.25
549.25
555.25
561.25
567.25
517.75
523.75
529.75
535.75
541.75
547.75
553.75
559.75
565.75
571.75
512–518
518–524
524–530
530–536
536–542
542–548
548–554
554–560
560–566
566–572
60
61
62
–
–
–
–
–
–
–
753.25
759.25
765.25
–
–
–
–
–
–
–
757.75
763.75
769.75
–
–
–
–
–
–
–
752–758
758–764
764–770
–
–
–
–
–
–
–
30
31
32
33
34
35
36
37
38
39
573.25
579.25
585.25
591.25
597.25
603.25
609.25
615.25
621.25
627.25
577.75
583.75
589.75
595.75
601.75
607.75
613.75
619.75
625.75
631.75
572–578
578–584
584–590
590–596
596–602
602–608
608–614
614–620
620–626
626–632

262 Chapter 8: NTSC, PAL, and SECAM Overview
Table 8.3a. Analog Cable TV Nominal Frequencies for USA for Incrementally Related
Carrier (IRC) Systems. For Harmonically Related Carrier (HRC) systems, subtract 1.25
MHz.
Cable
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
Cable
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
–
1
2
3
4
5
6
7
8
9
–
73.25
55.25
61.25
67.25
77.25
83.25
175.25
181.25
187.25
–
77.75
59.75
65.75
71.75
81.75
87.75
179.75
185.75
191.75
–
72–78
54–60
60–66
66–72
76–82
82–88
174–180
180–186
186–192
40
41
42
43
44
45
46
47
48
49
319.25
325.25
331.25
337.25
343.25
349.25
355.25
361.25
367.25
373.25
323.75
329.75
335.75
341.75
347.75
353.75
359.75
365.75
371.75
377.75
318–324
324–330
330–336
336–342
342–348
348–354
354–360
360–366
366–372
372–378
10
11
12
13
14
15
16
17
18
19
193.25
199.25
205.25
211.25
121.25
127.25
133.25
139.25
145.25
151.25
197.75
203.75
209.75
215.75
125.75
131.75
137.75
143.75
149.75
155.75
192–198
198–204
204–210
210–216
120–126
126–132
132–138
138–144
144–150
150–156
50
51
52
53
54
55
56
57
58
59
379.25
385.25
391.25
397.25
403.25
409.25
415.25
421.25
427.25
433.25
383.75
389.75
395.75
401.75
407.75
413.75
419.75
425.75
431.75
437.75
378–384
384–390
390–396
396–402
402–408
408–414
414–420
420–426
426–432
432–438
20
21
22
23
24
25
26
27
28
29
157.25
163.25
169.25
217.25
223.25
229.25
235.25
241.25
247.25
253.25
161.75
167.75
173.75
221.75
227.75
233.75
239.75
245.75
251.75
257.75
156–162
162–168
168–174
216–222
222–228
228–234
234–240
240–246
246–252
252–258
60
61
62
63
64
65
66
67
68
69
439.25
445.55
451.25
457.25
463.25
469.25
475.25
481.25
487.25
493.25
443.75
449.75
455.75
461.75
467.75
473.75
479.75
485.75
491.75
497.75
438–444
444–450
450–456
456–462
462–468
468–474
474–480
480–486
486–492
492–498
30
31
32
33
34
35
36
37
38
39
259.25
265.25
271.25
277.25
283.25
289.25
295.25
301.25
307.25
313.25
263.75
269.75
275.75
281.75
287.75
293.75
299.75
305.75
311.75
317.75
258–264
264–270
270–276
276–282
282–288
288–294
294–300
300–306
306–312
312–318
70
71
72
73
74
75
76
77
78
79
499.25
505.25
511.25
517.25
523.25
529.25
535.25
541.25
547.25
553.25
503.75
509.75
515.75
521.75
527.75
533.75
539.75
545.75
551.75
557.75
498–504
504–510
510–516
516–522
522–528
528–534
534–540
540–546
546–552
552–558

NTSC Overview 263
Table 8.3b. Analog Cable TV Nominal Frequencies for USA for Incrementally Related
Carrier (IRC) Systems. For Harmonically Related Carrier (HRC) systems, subtract
1.25 MHz. T channels are reverse (return) channels for two-way applications.
Cable
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
Cable
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
80
81
82
83
84
85
86
87
88
89
559.25
565.25
571.25
577.25
583.25
589.25
595.25
601.25
607.25
613.25
563.75
569.75
575.75
581.75
587.75
593.75
599.75
605.75
611.75
617.75
558–564
564–570
570–576
576–582
582–588
588–594
594–600
600–606
606–612
612–618
120
121
122
123
124
125
126
127
128
129
769.25
775.25
781.25
787.25
793.25
799.25
805.25
811.25
817.25
823.25
773.75
779.75
785.75
791.75
797.75
803.75
809.75
815.75
821.75
827.75
768–774
774–780
780–786
786–792
792–798
798–804
804–810
810–816
816–822
822–828
90
91
92
93
94
95
96
97
98
99
619.25
625.25
631.25
637.25
643.25
91.25
97.25
103.25
109.25
115.25
623.75
629.75
635.75
641.75
647.75
95.75
101.75
107.75
113.75
119.75
618–624
624–630
630–636
636–642
642–648
90–96
96–102
102–108
108–114
114–120
130
131
132
133
134
135
136
137
138
139
829.25
835.25
841.25
847.25
853.25
859.25
865.25
871.25
877.25
883.25
833.75
839.75
845.75
851.75
857.75
863.75
869.75
875.75
881.75
887.75
828–834
834–840
840–846
846–852
852–858
858–864
864–870
870–876
876–882
882–888
100
101
102
103
104
105
106
107
108
109
649.25
655.25
661.25
667.25
673.25
679.25
685.25
691.25
697.25
703.25
653.75
659.75
665.75
671.75
677.75
683.75
689.75
695.75
701.75
707.75
648–654
654–660
660–666
666–672
672–678
678–684
684–690
690–696
696–702
702–708
140
141
142
143
144
145
146
147
148
149
889.25
895.25
901.25
907.25
913.25
919.25
925.25
931.25
937.25
943.25
893.75
899.75
905.75
911.75
917.75
923.75
929.75
935.75
941.75
947.75
888–894
894–900
900–906
906–912
912–918
918–924
924–930
930–936
936–942
942–948
110
111
112
113
114
115
116
117
118
119
709.25
715.25
721.25
727.25
733.25
739.25
745.25
751.25
757.25
763.25
713.75
719.75
725.75
731.75
737.75
743.75
749.75
755.75
761.75
767.75
708–714
714–720
720–726
726–732
732–738
738–744
744–750
750–756
756–762
762–768
150
151
152
153
154
155
156
157
158
–
949.25
955.25
961.25
967.25
973.25
979.25
985.25
991.25
997.25
–
953.75
959.75
965.75
971.75
977.75
983.75
989.75
995.75
1001.75
–
948–954
954–960
960–966
966–972
972–978
978–984
984–990
990–996
996–1002
–
T7
T8
T9
T10
8.25
14.25
20.25
26.25
7–13
13–19
19–25
25–31
T11
T13
T13
–
32.25
38.25
44.25
–
31–37
37–43
43–49
–

264 Chapter 8: NTSC, PAL, and SECAM Overview
Table 8.4. Analog Cable TV Nominal Frequencies for Japan.
Cable
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
Cable
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
–
–
–
13
14
15
16
17
18
19
–
–
–
109.25
115.25
121.25
127.25
133.25
139.25
145.25
–
–
–
113.75
119.75
125.75
131.75
137.75
143.75
149.75
–
–
–
108–114
114–120
120–126
126–132
132–138
138–144
144–150
40
41
42
46
44
45
46
47
48
49
325.25
331.25
337.25
343.25
349.25
355.25
361.25
367.25
373.25
379.25
329.75
335.75
341.75
347.75
353.75
359.75
365.75
371.75
377.75
383.75
324–330
330–336
336–342
342–348
348–354
354–360
360–366
366–372
372–378
378–384
20
21
22
23
24
25
26
27
28
29
151.25
157.25
165.25
223.25
231.25
237.25
243.25
249.25
253.25
259.25
155.75
161.75
169.75
227.75
235.75
241.75
247.75
253.75
257.75
263.75
150–156
156–162
164–170
222–228
230–236
236–242
242–248
248–254
252–258
258–264
50
51
52
53
54
55
56
57
58
59
385.25
391.25
397.25
403.25
409.25
415.25
421.25
427.25
433.25
439.25
389.75
395.75
401.75
407.75
413.75
419.75
425.75
431.75
437.75
443.75
384–390
390–396
396–402
402–408
408–414
414–420
420–426
426–432
432–438
438–444
30
31
32
33
34
35
36
37
38
39
265.25
271.25
277.25
283.25
289.25
295.25
301.25
307.25
313.25
319.25
269.75
275.75
281.75
287.75
293.75
299.75
305.75
311.75
317.75
323.75
264–270
270–276
276–282
282–288
288–294
294–300
300–306
306–312
312–318
318–324
60
61
62
63
–
–
–
–
–
–
445.25
451.25
457.25
463.25
–
–
–
–
–
–
449.75
455.75
461.75
467.75
–
–
–
–
–
–
444–450
450–456
456–462
462–468
–
–
–
–
–
–

The following countries use the (M) NTSC
standard.
Antigua Japan (NTSC–J)
Aruba Korea, South
Bahamas Mexico
Barbados Montserrat
Belize Myanmar
Bermuda Nicaragua
Bolivia Panama
Canada Peru
Chile Philippines
Colombia Puerto Rico
Costa Rica St. Kitts and Nevis
Cuba Samoa
Curacao Suriname
Dominican Republic Taiwan
Ecuador Trinidad/Tobago
El Salvador United States of
Guam America
Guatemala Venezuela
Honduras Virgin Islands
Jamaica
Luminance Equation Derivation
The equation for generating luminance from
RGB is determined by the chromaticities of the
three primary colors used by the receiver and
what color white actually is.
The chromaticities of the RGB primaries
and reference white (CIE illuminate C) were
specified in the 1953 NTSC standard to be:
R: xr =0.67 yr = 0.33 zr = 0.00
G: xg = 0.21 yg =0.71zg =0.08
B: xb = 0.14 yb =0.08zb =0.78
white: xw = 0.3101
zw = 0.3737
yw = 0.3162
NTSC Overview 265
where x and y are the specified CIE 1931 chromaticity
coordinates; z is calculated by knowing
that x + y + z = 1.
Luminance is calculated as a weighted sum
of RGB, with the weights representing the
actual contributions of each of the RGB primaries
in generating the luminance of reference
white. We find the linear combination of RGB
that gives reference white by solving the equation:
xr xg xb yr yg yb zr zg zb Kr Kg Kb xw ⁄ yw 1
zw ⁄ yw Rearranging to solve for K r ,K g ,andK b yields:
K r
K g
K b
xw ⁄ yw 1
zw ⁄ yw Substituting the known values gives us the
solution for K r ,K g ,andK b :
K r
K g
K b
=
=
=
=
=
0.3101 ⁄ 0.3162
1
0.3737 ⁄ 0.3162
0.9807
1
1.1818
0.906
0.827
1.430
=
x r x g x b
y r y g y b
z r z g z b
– 1
0.67 0.21 0.14
0.33 0.71 0.08
0.00 0.08 0.78
1.730 – 0.482 – 0.261
– 0.814 1.652 – 0.023
0.083 – 0.169 1.284
– 1

266 Chapter 8: NTSC, PAL, and SECAM Overview
Y is defined to be
or
Y=(K r y r )R´ +(K g y g )G´ +(K b y b )B´
= (0.906)(0.33)R´ + (0.827)(0.71)G´
+ (1.430)(0.08)B´
Y = 0.299R´ + 0.587G´ + 0.114B´
Modern receivers use a different set of
RGB phosphors, resulting in slightly different
chromaticities of the RGB primaries and reference
white (CIE illuminate D 65 ):
R: xr = 0.630 yr = 0.340 zr = 0.030
G: xg = 0.310 yg = 0.595 zg = 0.095
B: xb = 0.155 yb = 0.070 zb = 0.775
white: xw = 0.3127
zw = 0.3583
yw = 0.3290
where x and y are the specified CIE 1931 chromaticity
coordinates; z is calculated by knowing
that x + y + z = 1. Once again, substituting
the known values gives us the solution for K r ,
K g ,andK b :
Kr Kg Kb =
=
=
0.3127 ⁄ 0.3290
1
0.3583 ⁄ 0.3290
0.6243
1.1770
1.2362
0.630 0.310 0.155
0.340 0.595 0.070
0.030 0.095 0.775
– 1
Since Y is defined to be
Y=(K r y r )R´ +(K g y g )G´ +(K b y b )B´
= (0.6243)(0.340)R´ + (1.1770)(0.595)G´
+ (1.2362)(0.070)B´
this results in:
Y = 0.212R´ + 0.700G´ +0.086B´
However, the standard Y = 0.299R´ +
0.587G´ + 0.114B´ equation is still used. Adjustments
are in the receiver to minimize color
errors.
PAL Overview
Europe delayed adopting a color television
standard, evaluating various systems between
1953 and 1967 that were compatible with their
625-line, 50-field-per-second, 2:1 interlaced
monochrome standard. The NTSC specification
was modified to overcome the high order
of phase and amplitude integrity required during
broadcast to avoid color distortion. The
Phase Alternation Line (PAL) system implements
a line-by-line reversal of the phase of
one of the color components, originally relying
on the eye to average any color distortions to
the correct color. Broadcasting began in 1967
in Germany and the United Kingdom, with
each using a slightly different variant of the
PAL system.

Luminance Information
The monochrome luminance (Y) signal is
derived from R´G´B´:
Y = 0.299R´ + 0.587G´ + 0.114B´
As with NTSC, the luminance signal occupies
the entire video bandwidth. PAL has several
variations, depending on the video
bandwidth and placement of the audio subcarrier.
The composite video signal has a bandwidth
of 4.2, 5.0, 5.5, or 6.0 MHz, depending on
the specific PAL standard.
Color Information
To transmit color information, U and V are
used:
U = 0.492(B´ –Y)
V = 0.877(R´ –Y)
U and V have a typical bandwidth of 1.3 MHz.
Color Modulation
As in the NTSC system, U and V are used to
modulate the color subcarrier using two balanced
modulators operating in phase quadrature:
one modulator is driven by the subcarrier
at sine phase, the other modulator is driven by
the subcarrier at cosine phase. The outputs of
the modulators are added together to form the
modulated chrominance signal:
C=Usinωt ± Vcosωt
ω =2πFSC F SC = 4.43361875 MHz (± 5Hz)
for (B, D, G, H, I, N) PAL
F SC = 3.58205625 MHz (± 5Hz)for
(N C )PAL
PAL Overview 267
F SC = 3.57561149 MHz (± 10 Hz) for
(M) PAL
In PAL, the phase of V is reversed every
other line. V was chosen for the reversal process
since it has a lower gain factor than U and
therefore is less susceptible to a one-half F H
switching rate imbalance. The result of alternating
the V phase at the line rate is that any
color subcarrier phase errors produce complementary
errors, allowing line-to-line averaging
at the receiver to cancel the errors and generate
the correct hue with slightly reduced saturation.
This technique requires the PAL
receiver to be able to determine the correct V
phase. This is done using a technique known
as AB sync, PAL sync, PAL Switch, or “swinging
burst,” consisting of alternating the phase
of the color burst by ±45° atthelinerate.The
UV vector diagrams are shown in Figures 8.11
and 8.12.
“Simple” PAL decoders rely on the eye to
average the line-by-line hue errors. “Standard”
PAL decoders use a 1-H delay line to separate
U from V in an averaging process. Both implementations
have the problem of Hanover bars,
in which pairs of adjacent lines have a real and
complementary hue error. Chrominance vertical
resolution is reduced as a result of the line
averaging process.
Composite Video Generation
The modulated chrominance is added to the
luminance information along with appropriate
horizontal and vertical sync signals, blanking
signals, and color burst signals, to generate the
composite color video waveform shown in Figure
8.13.
compositePAL=Y+Usinωt
± Vcosωt+timing

268 Chapter 8: NTSC, PAL, and SECAM Overview
YELLOW
167˚
YELLOW
193˚
BURST
135˚
67
GREEN
241˚
GREEN
120˚
RED
103˚
95
+ V
90˚
100
80
60
40
20
89 95
RED
257˚
+ V
90˚
CYAN
283˚
IRE SCALE UNITS
CYAN
77˚
89
MAGENTA
61˚
67
MAGENTA
300˚
+ U
0˚
BLUE
347˚
Figure 8.11. UV Vector Diagram for 75% Color Bars. Line [n],
PAL Switch = zero.
BURST
225˚
67
89
95
40
20
100
80
60
IRE SCALE UNITS
Figure 8.12. UV Vector Diagram for 75% Color Bars. Line [n
+ 1], PAL Switch = one.
95
89
67
BLUE
13˚
+ U
0˚

100 IRE
43 IRE
21.43 IRE
21.43 IRE
COLOR BURST
(10 ± 1 CYCLES)
BLANK LEVEL
LUMINANCE LEVEL
Figure 8.13. (B, D, G, H, I, N C)PALComposite
Video Signal for 75% Color Bars.
WHITE
YELLOW
CYAN
GREEN
MAGENTA
RED
BLUE
PHASE = HUE
PAL Overview 269
BLACK
WHITE LEVEL
BLACK / BLANK LEVEL
SYNC LEVEL
COLOR
SATURATION

270 Chapter 8: NTSC, PAL, and SECAM Overview
The bandwidth of the resulting composite
video signal is shown in Figure 8.14.
Like NTSC, the luminance components are
spaced at F H intervals due to horizontal blanking.
Since the V component is switched symmetrically
at one-half the line rate, only odd
harmonics are generated, resulting in V components
that are spaced at intervals of F H .The
V components are spaced at half-line intervals
from the U components, which also have F H
spacing. If the subcarrier had a half-line offset
like NTSC uses, the U components would be
perfectly interleaved, but the V components
would coincide with the Y components and
thus not be interleaved, creating vertical stationary
dot patterns. For this reason, PAL uses
a 1/4 line offset for the subcarrier frequency:
FSC = ((1135/4) + (1/625)) FH for (B, D, G, H, I, N) PAL
FSC = (909/4) FH for (M) PAL
F SC = ((917/4) + (1/625)) F H
for (N C )PAL
The additional (1/625) F H factor (equal to
25 Hz) provides motion to the color dot pattern,
reducing its visibility. Figure 8.15 illustrates
the resulting frequency interleaving.
Eight complete fields are required to repeat a
specific sample position, as shown in Figures
8.16 and 8.17.
PAL Variations
There is a variation of PAL, “noninterlaced
PAL”, shown in Figure 8.18. It is a 312-line, 50
frames-per-second version of PAL common
among video games and on-screen displays.
This format is identical to standard PAL,
except that there are 312 lines per frame.
The most common PAL standards are
showninFigure8.19.
RF Modulation
Figures 8.20 and 8.21 illustrate the process of
converting baseband (G) PAL composite video
to a RF (radio frequency) signal. The process
for the other PAL standards is similar, except
primarily the different video bandwidths and
subcarrier frequencies.
Figure 8.20a shows the frequency spectrum
of a (G) PAL baseband composite video
signal. It is similar to Figure 8.14, however, Figure
8.14 only shows the upper sideband for
simplicity. The “video carrier” notation at 0
MHz serves only as a reference point for comparison
with Figure 8.20b.
Figure 8.20b shows the audio/video signal
as it resides within an 8-MHz channel. The
video signal has been lowpass filtered, most of
the lower sideband has been removed, and
audio information has been added. Note that
(H) and (I) PAL have a vestigial sideband of
1.25 MHz, rather than 0.75 MHz.
Figure 8.20c details the information
present on the audio subcarrier for analog stereo
operation.
As shown in Figure 8.21, back porch clamping
of the analog video signal ensures that the
back porch level is constant, regardless of
changes in the average picture level. The video
signal is then lowpass filtered to 5.0 MHz and
drives the AM (amplitude modulation) video
modulator. The sync level corresponds to 100%
modulation; the blanking and white modulation
levels are dependent on the specific version of
PAL:

AMPLITUDE
Y U
± V
CHROMINANCE
SUBCARRIER
U
± V
0.0 1.0
2.0 3.0 4.0 4.43 5.0 5.5
AMPLITUDE
0.0
(I) PAL
Y U
± V
CHROMINANCE
SUBCARRIER
U
± V
1.0 2.0 3.0 4.0 4.43 5.0
(B, G, H) PAL
Figure 8.14. Video Bandwidths of Some PAL Systems.
FH / 4
U
Y
V
FH / 2
FH
U
Y
V
F
PAL Overview 271
FREQUENCY
(MHZ)
FREQUENCY
(MHZ)
Figure 8.15. Luma and Chroma Frequency Interleave Principle.

272 Chapter 8: NTSC, PAL, and SECAM Overview
BURST
BLANKING
INTERVALS
START
OF
VSYNC
ANALOG
FIELD 1
620 621 622 623 624 625 1 2 3 4 5 6 7 23 24
–U COMPONENT OF BURST PHASE
ANALOG
FIELD 2
308 309 310 311 312 313 314 315 316 317 318 319 320 336 337
ANALOG
FIELD 3
620 621 622 623 624 625 1 2 3 4 5 6 7 23 24
ANALOG
FIELD 4
308 309 310 311 312 313 314 315 316 317 318 319 320 336 337
FIELD ONE
FIELD TWO
FIELD THREE
FIELD FOUR
BURST PHASE = REFERENCE PHASE = 135˚ RELATIVE TO U
PAL SWITCH = 0, + V COMPONENT
BURST PHASE = REFERENCE PHASE + 90˚ = 225˚ RELATIVE TO U
PAL SWITCH = 1, – V COMPONENT
Figure8.16a.Eight-field(B,D,G,H,I,N C ) PAL Sequence and Burst Blanking.
See Figure 8.5 for equalization and serration pulse details.

BURST
BLANKING
INTERVALS
START
OF
VSYNC
ANALOG
FIELD 5
–U COMPONENT OF BURST PHASE
BURST PHASE = REFERENCE PHASE = 135˚ RELATIVE TO U
PAL SWITCH = 0, + V COMPONENT
BURST PHASE = REFERENCE PHASE + 90˚ = 225˚ RELATIVE TO U
PAL SWITCH = 1, – V COMPONENT
PAL Overview 273
620 621 622 623 624 625 1 2 3 4 5 6 7 23 24
ANALOG
FIELD 6
308 309 310 311 312 313 314 315 316 317 318 319 320 336 337
ANALOG
FIELD 7
620 621 622 623 624 625 1 2 3 4 5 6 7 23 24
ANALOG
FIELD 8
308 309 310 311 312 313 314 315 316 317 318 319 320 336 337
FIELD FIVE
FIELD SIX
FIELD SEVEN
FIELD EIGHT
Figure8.16b.Eight-field(B,D,G,H,I,N C ) PAL Sequence and Burst Blanking.
See Figure 8.5 for equalization and serration pulse details.

274 Chapter 8: NTSC, PAL, and SECAM Overview
START
OF
VSYNC
ANALOG
FIELD 1 / 5
520 521 522 523 524 525 1 2 3 4 5 6 7 8 9
ANALOG
FIELD 2 / 6
258 259 260 261 262 263 264 265 266 267 268 269 270 271 272
ANALOG
FIELD 3 / 7
520 521 522 523 524 525 1 2 3 4 5 6 7 8 9
ANALOG
FIELD 4 / 8
258 259 260 261 262 263 264 265 266 267 268 269 270 271 272
BURST PHASE = REFERENCE PHASE = 135˚ RELATIVE TO U
PAL SWITCH = 0, + V COMPONENT
BURST PHASE = REFERENCE PHASE + 90˚ = 225˚ RELATIVE TO U
PAL SWITCH = 1, – V COMPONENT
Figure 8.17. Eight-field (M) PAL Sequence and Burst Blanking.
See Figure 8.5 for equalization and serration pulse details.

START
OF
VSYNC
BURST PHASE = REFERENCE PHASE = 135˚ RELATIVE TO U
PAL SWITCH = 0, + V COMPONENT
BURST PHASE = REFERENCE PHASE + 90˚ = 225˚ RELATIVE TO U
PAL SWITCH = 1, – V COMPONENT
PAL Overview 275
308 309 310 311 312 1 2 3 4 5 6 7 23 24
blanking level (% modulation)
B, G 75%
D, H, M, N 75%
I 76%
white level (% modulation)
B, G, H, M, N 10%
D 10%
I 20%
Note that PAL systems use a variety of
video and audio IF frequencies (values in
MHz):
video audio
B, G 38.900 33.400
B 36.875 31.375 Australia
D 37.000 30.500 China
D 38.900 32.400 OIRT
I 38.900 32.900
I 39.500 33.500 U.K.
M, N 45.750 41.250
Figure 8.18. Noninterlaced PAL Frame Sequence.
At this point, audio information is added on
the audio subcarrier. A monaural L+R audio
signal is processed as shown in Figure 8.21
and drives the FM (frequency modulation)
modulator. The output of the FM modulator is
added to the IF video signal.
The SAW filter, used as a vestigial sideband
filter, provides filtering of the IF signal.
The mixer, or up converter, mixes the IF signal
with the desired broadcast frequency. Both
sum and difference frequencies are generated
by the mixing process, so the difference signal
isextractedbyusingabandpassfilter.
Stereo Audio (Analog)
The implementation of analog stereo audio
(ITU-R BS.707), also know as Zweiton, is
shown in Figure 8.21. The L+R information is
transmitted on a FM subcarrier. The R information,
or a second L+R audio signal, is transmitted
on a second FM subcarrier at +15.5F H .
If stereo or dual mono signals are present,
the FM subcarrier at +15.5F H is amplitude-

276 Chapter 8: NTSC, PAL, and SECAM Overview
"I"
LINE / FIELD = 625 / 50
FH = 15.625 KHZ
FV = 50 HZ
FSC = 4.43361875 MHZ
BLANKING SETUP = 0 IRE
VIDEO BANDWIDTH = 5.5 MHZ
AUDIO CARRIER = 5.9996 MHZ
CHANNEL BANDWIDTH = 8 MHZ
"D"
LINE / FIELD = 625 / 50
FH = 15.625 KHZ
FV = 50 HZ
FSC = 4.43361875 MHZ
BLANKING SETUP = 0 IRE
VIDEO BANDWIDTH = 6.0 MHZ
AUDIO CARRIER = 6.5 MHZ
CHANNEL BANDWIDTH = 8 MHZ
QUADRATURE MODULATED SUBCARRIER
PHASE = HUE
AMPLITUDE = SATURATION
LINE ALTERNATION OF V COMPONENT
"B, B1, G, H"
LINE / FIELD = 625 / 50
FH = 15.625 KHZ
FV = 50 HZ
FSC = 4.43361875 MHZ
BLANKING SETUP = 0 IRE
VIDEO BANDWIDTH = 5.0 MHZ
AUDIO CARRIER = 5.5 MHZ
CHANNEL BANDWIDTH:
B = 7 MHZ
B1, G, H = 8 MHZ
"N"
LINE / FIELD = 625 / 50
FH = 15.625 KHZ
FV = 50 HZ
FSC = 4.43361875 MHZ
BLANKING SETUP = 7.5 IRE
VIDEO BANDWIDTH = 5.0 MHZ
AUDIO CARRIER = 5.5 MHZ
CHANNEL BANDWIDTH = 6 MHZ
Figure 8.19. Common PAL Systems.
"M"
LINE / FIELD = 525 / 59.94
FH = 15.734 KHZ
FV = 59.94 HZ
FSC = 3.57561149 MHZ
BLANKING SETUP = 7.5 IRE
VIDEO BANDWIDTH = 4.2 MHZ
AUDIO CARRIER = 4.5 MHZ
CHANNEL BANDWIDTH = 6 MHZ
"N C "
LINE / FIELD = 625 / 50
FH = 15.625 KHZ
FV = 50 HZ
FSC = 3.58205625 MHZ
BLANKING SETUP = 0 IRE
VIDEO BANDWIDTH = 4.2 MHZ
AUDIO CARRIER = 4.5 MHZ
CHANNEL BANDWIDTH = 6 MHZ

–5.5
CHROMINANCE
SUBCARRIER
–5.0
–4.43
VIDEO
CARRIER
–1.0 0.0
1.0
4.43 5.0 5.5
VIDEO
CARRIER
(A)
8 MHZ CHANNEL
CHROMINANCE
SUBCARRIER
CHROMINANCE
SUBCARRIER
–4.0 –3.0 –0.75 0.0
1.0
4.43 5.0 5.5
AUDIO
CARRIER
L + R
(FM)
0.75 MHZ
VESTIGIAL
SIDEBAND
–1.25
FH = 15,625 HZ
(B)
R
(FM)
–50 KHZ 0.0 50 KHZ
15.5 FH
– 50 KHZ
15.5 FH
(C)
AUDIO
CARRIER
15.5 FH
+ 50 KHZ
6.75
PAL Overview 277
FREQUENCY (MHZ)
FREQUENCY (MHZ)
FREQUENCY
Figure 8.20. Transmission Channel for (G) PAL. (a) Frequency spectrum of baseband composite
video. (b) Frequency spectrum of typical channel including audio information. (c) Detailed
frequency spectrum of Zweiton analog stereo audio information.

278 Chapter 8: NTSC, PAL, and SECAM Overview
modulated with a 54.6875 kHz (3.5x F H )subcarrier.
This 54.6875 kHz subcarrier is 50%
amplitude-modulated at 117.5 Hz (F H / 133) to
indicate stereo audio or 274.1 Hz (F H / 57) to
indicate dual mono audio.
Countries that use this system include
Australia, Austria, China, Germany, Italy,
Malaysia, Netherlands, Slovenia, and Switzerland.
Stereo Audio (Digital)
The implementation of digital stereo audio
uses NICAM 728 (Near Instantaneous Companded
Audio Multiplex), discussed within
BS.707 and ETSI EN 300163. It was developed
by the BBC and IBA to increase sound quality,
provide multiple channels of digital sound or
AUDIO RIGHT
AUDIO LEFT
(G) PAL
COMPOSITE
VIDEO
BACK
PORCH
CLAMP
STEREO
PILOT SIGNAL
50 µS
PRE-EMPHASIS
---------------
40–15,000 HZ BPF
L + R
---------------
50 µS
PRE-EMPHASIS
---------------
40–15,000 HZ BPF
5.0 MHZ
LPF
3.5FH
AM
MODULATOR
38.9 MHZ
IF VIDEO CARRIER
117.5 HZ
274.1 HZ
AM
MODULATOR
FM
MODULATOR
33.4 MHZ – 15.5FH
IF AUDIO CARRIER
FM
MODULATOR
33.4 MHZ
IF AUDIO CARRIER
data, and be more resistant to transmission
interference.
The subcarrier resides either 5.85 MHz
above the video carrier for (B, G, H) PAL systems
or 6.552 MHz above the video carrier for
(I) PAL systems.
Countries that use NICAM 728 include
Belgium, Denmark, Finland, France, Hong
Kong, New Zealand, Norway, Singapore, South
Africa, Spain, Sweden, and the United Kingdom.
NICAM 728 is a digital system that uses a
32-kHz sampling rate and 14-bit resolution. A
bit rate of 728 kbps is used, giving it the name
NICAM 728. Data is transmitted in frames,
with each frame containing 1 ms of audio. As
shown in Figure 8.22, each frame consists of:
+
AM
MODULATOR
SAW
FILTER
33.15–40.15 MHZ
BANDWIDTH
+
MIXER
(UP CONVERTER)
CHANNEL
SELECT
BANDPASS
FILTER
Figure 8.21. Typical RF Modulation Implementation for (G) PAL: Zweiton Stereo Audio.
MODULATED RF
AUDIO / VIDEO

8-bit frame alignment word (01001110)
5 control bits (C0–C4)
11 undefined bits (AD0–AD10)
704 audio data bits (A000–A703)
C0 is a “1” for eight successive frames and
a “0” for the next eight frames, defining a 16frame
sequence. C1–C3 specify the format
transmitted: “000” = one stereo signal with the
left channel being odd-numbered samples and
the right channel being even-numbered samples,
“010” = two independent mono channels
transmitted in alternate frames, “100” = one
mono channel and one 352 kbps data channel
transmitted in alternate frames, “110” = one
704 kbps data channel. C4 is a “1” if the analog
sound is the same as the digital sound.
Stereo Audio Encoding
The thirty-two 14-bit samples (1 ms of audio,
2’s complement format) per channel are preemphasized
to the ITU-T J.17 curve.
The largest positive or negative sample of
the32isusedtodeterminewhich10bitsofall
32 samples to transmit. Three range bits per
channel (R0 L ,R1 L ,R2 L ,andR0 R ,R1 R ,R2 R )are
used to indicate the scaling factor. D13 is the
sign bit (“0” = positive).
D13–D0 R2–R0 Bits Used
01xxxxxxxxxxxx 111 D13, D12–D4
001xxxxxxxxxxx 110 D13, D11–D3
0001xxxxxxxxxx 101 D13, D10–D2
00001xxxxxxxxx 011 D13, D9–D1
000001xxxxxxxx 101 D13, D8–D0
0000001xxxxxxx 010 D13, D8–D0
0000000xxxxxxx 00x D13, D8–D0
1111111xxxxxxx 00x D13, D8–D0
1111110xxxxxxx 010 D13, D8–D0
111110xxxxxxxx 100 D13, D8–D0
11110xxxxxxxxx 011 D13, D9–D1
1110xxxxxxxxxx 101 D13, D10–D2
110xxxxxxxxxxx 110 D13, D11–D3
10xxxxxxxxxxxx 111 D13, D12–D4
PAL Overview 279
A parity bit for the six MSBs of each sample
is added, resulting in each sample being 11
bits. The 64 samples are interleaved, generating
L0, R0, L1, R1, L2, R2, ... L31, R31, and
numbered 0–63.
Theparitybitsareusedtoconveytothe
decoder what scaling factor was used for each
channel (“signalling-in-parity”).
If R2 L = “0”, even parity for samples
0, 6, 12, 18, ... 48 is used. If R2 L = “1”,
odd parity is used.
If R2 R = “0”, even parity for samples
1, 7, 13, 19, ... 49 is used. If R2 R = “1”,
odd parity is used.
If R1 L = “0”, even parity for samples
2, 8, 14, 20, ... 50 is used. If R1 L = “1”,
odd parity is used.
If R1 R = “0”, even parity for samples
3, 9, 15, 21, ... 51 is used. If R1 R = “1”,
odd parity is used.
If R0 L = “0”, even parity for samples
4, 10, 16, 22, ... 52 is used. If R0 L = “1”,
odd parity is used.
If R0 R = “0”, even parity for samples
5, 11, 17, 23, ... 53 is used. If R0 R = “1”,
odd parity is used.
Theparityofsamples54–63 normally have
even parity. However, they may be modified to
transmit two additional bits of information:
If CIB0 = “0”, even parity for samples
54, 55, 56, 57, and 58 is used. If CIB0 =
“1”, oddparityisused.
If CIB1 = “0”, even parity for samples
59, 60, 61, 62, and 63 is used. If CIB1 =
“1”, oddparityisused.

280 Chapter 8: NTSC, PAL, and SECAM Overview
The audio data is bit-interleaved as shown
in Figure 8.22 to reduce the influence of dropouts.
If the bits are numbered 0–703, they are
transmitted in the order 0, 44, 88, ... 660, 1, 45,
89, ... 661, 2, 46, 90, ... 703.
The whole frame, except the frame alignment
word, is exclusive-ORed with a 1-bit
pseudo-random binary sequence (PRBS). The
PRBS generator is reinitialized after the frame
alignment word of each frame so that the first
bit of the sequence processes the C0 bit. The
polynomial of the PRBS is x 9 +x 4 +1withan
initialization word of “111111111”.
Actual transmission consists of taking bits
in pairs from the 728 kbps bitstream, then generating
356k symbols per second using Differential
Quadrature Phase-Shift Keying
(DQPSK). If the symbol is “00”, thesubcarrier
phase is left unchanged. If the symbol is “01”,
the subcarrier phase is delayed 90°. Ifthesymbol
is “11”, the subcarrier phase is inverted. If
the symbol is “10”, the subcarrier phase is
advanced 90°.
Finally, the signal is spectrum-shaped to a
–30 dB bandwidth of ~700 kHz for (I) PAL or
~500 kHz for (B, G) PAL.
FRAME
ALIGNMENT
WORD
CONTROL
BITS ADDITIONAL DATA BITS
Stereo Audio Decoding
A PLL locks to the NICAM subcarrier frequency
and recovers the phase changes that
represent the encoded symbols. The symbols
are decoded to generate the 728 kbps bitstream.
The frame alignment word is found and
the following bits are exclusive-ORed with a
locally-generated PRBS to recover the packet.
The C0 bit is tested for 8 frames high, 8 frames
low behavior to verify it is a NICAM 728 bitstream.
The bit-interleaving of the audio data is
reversed, and the “signalling-in-parity”
decoded:
A majority vote is taken on the parity
ofsamples0,6,12,...48.Ifeven,R2 L =
“0”; ifodd,R2 L = “1”.
A majority vote is taken on the parity
of samples 1, 7, 13, ... 49. If even, R2 R =
“0”; ifodd,R2 R = “1”.
A majority vote is taken on the parity
ofsamples2,8,14,...50.Ifeven,R1 L =
“0”; ifodd,R1 L = “1”.
704 BITS
AUDIO DATA
0, 1, 0, 0, 1, 1, 1, 0, C0, C1, C2, C3, C4, AD0, AD1, AD2, AD3, AD4, AD5, AD6, AD7, AD8, AD9, AD10, A000, A044, A088, ... A660,
A001, A045, A089, ... A661,
A002, A046, A090, ... A662,
A003, A047, A091, ... A663,
:
A043, A087, A131, ... A703
Figure 8.22. NICAM 728 Bitstream for One Frame.

Amajorityvoteistakenontheparity
of samples 3, 9, 15, ... 51. If even, R1 R =
“0”; if odd, R1 R = “1”.
Amajorityvoteistakenontheparity
of samples 4, 10, 16, ... 52. If even, R0 L =
“0”; if odd, R0 L = “1”.
Amajorityvoteistakenontheparity
of samples 5, 11, 17, ... 53. If even, R0 R =
“0”; if odd, R0 R = “1”.
Amajorityvoteistakenontheparity
of samples 54, 55, 56, 57, and 58. If even,
CIB0 = “0”; if odd, CIB0 = “1”.
Amajorityvoteistakenontheparity
of samples 59, 60, 61, 62, and 63. If even,
CIB1 = “0”; if odd, CIB1 = “1”.
Anysampleswhoseparitydisagreedwith
the vote are ignored and replaced with an
interpolated value.
The left channel uses range bits R2 L ,R1 L ,
and R0 L to determine which bits below the
sign bit were discarded during encoding. The
sign bit is duplicated into those positions to
generate a 14-bit sample.
The right channel is similarly processed,
using range bits R2 R ,R1 R ,andR0 R .Bothchannels
are then de-emphasized using the J.17
curve.
Dual Mono Audio Encoding
Two blocks of thirty-two 14-bit samples (2 ms
of audio, 2’s complement format) are preemphasized
to the ITU-T J.17 specification. As
with the stereo audio, three range bits per
block (R0 A ,R1 A ,R2 A ,andR0 B ,R1 B ,R2 B )are
used to indicate the scaling factor. Unlike stereo
audio, the samples are not interleaved.
PAL Overview 281
If R2 A = “0”, even parity for samples
0, 3, 6, 9, ... 24 is used. If R2 A = “1”, odd
parity is used.
If R2 B = “0”, even parity for samples
27, 30, 33, ... 51 is used. If R2 B = “1”, odd
parity is used.
If R1 A = “0”, even parity for samples
1, 4, 7, 10, ... 25 is used. If R1 A = “1”, odd
parity is used.
If R1 B = “0”, even parity for samples
28, 31, 34, ... 52 is used. If R1 B = “1”, odd
parity is used.
If R0 A = “0”, even parity for samples
2, 5, 8, 11, ... 26 is used. If R0 A = “1”, odd
parity is used.
If R0 B = “0”, even parity for samples
29, 32, 35, ... 53 is used. If R0 B = “1”, odd
parity is used.
The audio data is bit-interleaved, however,
odd packets contain 64 samples of audio channel
1 while even packets contain 64 samples of
audio channel 2. The rest of the processing is
thesameasforstereoaudio.
Analog Channel Assignments
Tables 8.5 through 8.7 list the channel assignments
for VHF, UHF, and cable for various PAL
systems.
Note that cable systems routinely reassign
channel numbers to alternate frequencies to
minimize interference and provide multiple
levels of programming (such as two versions of
a premium movie channel: one for subscribers,
and one for nonsubscribers during pre-view
times).

282 Chapter 8: NTSC, PAL, and SECAM Overview
Channel
0
1
2
3
4
5
5A
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
(B) PAL, Australia, 7 MHz Channel (B) PAL, Italy, 7 MHz Channel
46.25
57.25
64.25
86.25
95.25
102.25
138.25
175.25
182.25
189.25
196.25
209.25
216.25
223.25
51.75
62.75
69.75
91.75
100.75
107.75
143.75
180.75
187.75
194.75
201.75
214.75
221.75
45–52
56–63
63–70
85–92
94–101
101–108
137–144
174–181
181–188
188–195
195–202
208–215
215–222
Channel
Range
(MHz)
Table 8.5. Analog Broadcast and Cable TV Nominal Frequencies for (B, I) PAL in Various Countries.
A
B
C
D
E
F
G
H
H–1
H–2
–
–
–
–
53.75
62.25
82.25
175.25
183.75
192.25
201.25
210.25
217.25
224.25
–
–
–
–
59.25
67.75
87.75
180.75
189.25
197.75
206.75
215.75
222.75
229.75
–
–
–
–
(I) PAL, Ireland, 8 MHz Channel (B) PAL, New Zealand, 7 MHz Channel
45.75
53.75
61.75
175.25
183.25
191.25
199.25
207.25
215.25
51.75
59.75
67.75
181.25
189.25
197.25
205.25
213.25
221.25
44.5–52.5
52.5–60.5
60.5–68.5
174–182
182–190
190–198
198–206
206–214
214–222
1
2
3
4
5
6
7
8
9
45.25
55.25
62.25
175.25
182.25
189.25
196.25
203.25
210.25
50.75
60.75
67.75
180.75
187.75
194.75
201.75
208.75
215.75
52.5–59.5
61–68
81–88
174–181
182.5–189.5
191–198
200–207
209–216
216–223
223–230
–
–
–
–
44–51
54–61
61–68
174–181
181–188
188–195
195–202
202–209
209–216

Broadcast
Channel
2 1
3 1
4 1
5 1
6 1
7 1
8 1
9 1
10 1
2 2
3 2
4 2
5 2
6 2
7 2
8 2
9 2
10 2
11 2
12 2
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
Video
Carrier
(MHz)
45.75
53.75
61.75
175.25
183.25
191.25
199.25
207.25
215.25
48.25
55.25
62.25
175.25
182.25
189.25
196.25
203.25
210.25
217.25
224.25
471.25
479.25
487.25
495.25
503.25
511.25
519.25
527.25
535.25
543.25
551.25
559.25
567.25
575.25
583.25
591.25
599.25
607.25
615.25
Audio
Carrier
(MHz)
(G,H)PAL (I)PAL
51.25
59.25
67.25
180.75
188.75
196.75
204.75
212.75
220.75
53.75
60.75
67.75
180.75
187.75
194.75
201.75
208.75
215.75
222.75
229.75
476.75
484.75
492.75
500.75
508.75
516.75
524.75
532.75
540.75
548.75
556.75
564.75
572.75
580.75
588.75
596.75
604.75
612.75
620.75
51.75
59.75
67.75
181.25
189.25
197.25
205.25
213.25
221.25
Channel
Range
(MHz)
44.5–52.5
52.5–60.5
60.5–68.5
174–182
182–190
190–198
198–206
206–214
214–222
Table 8.6a. Analog Broadcast Nominal Frequencies for the
1 United Kingdom, 1 Ireland, 1 South Africa, 1 Hong Kong, and
2 Western Europe.
–
–
–
–
–
–
–
–
–
–
–
477.25
485.25
493.25
501.25
509.25
517.25
525.25
533.25
541.25
549.25
557.25
565.25
573.25
581.25
589.25
597.25
605.25
613.25
621.25
47–54
54–61
61–68
174–181
181–188
188–195
195–202
202–209
209–216
216–223
223–230
470–478
478–486
486–494
494–502
502–510
510–518
518–526
526–534
534–542
542–550
550–558
558–566
566–574
574–582
582–590
590–598
598–606
606–614
614–622
PAL Overview 283

284 Chapter 8: NTSC, PAL, and SECAM Overview
Broadcast
Channel
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
Video
Carrier
(MHz)
623.25
631.25
639.25
647.25
655.25
663.25
671.25
679.25
687.25
695.25
703.25
711.25
719.25
727.25
735.25
743.25
751.25
759.25
767.25
775.25
783.25
791.25
799.25
807.25
815.25
823.25
831.25
839.25
847.25
855.25
Audio
Carrier
(MHz)
(G,H)PAL (I)PAL
628.75
636.75
644.75
652.75
660.75
668.75
676.75
684.75
692.75
700.75
708.75
716.75
724.75
732.75
740.75
748.75
756.75
764.75
772.75
780.75
788.75
796.75
804.75
812.75
820.75
828.75
836.75
844.75
852.75
860.75
629.25
637.25
645.25
653.25
661.25
669.25
677.25
685.25
693.25
701.25
709.25
717.25
725.25
733.25
741.25
749.25
757.25
765.25
773.25
781.25
789.25
797.25
805.25
813.25
821.25
829.25
837.25
845.25
853.25
861.25
Channel
Range
(MHz)
622–630
630–638
638–646
646–654
654–662
662–670
670–678
678–686
686–694
694–702
702–710
710–718
718–726
726–734
734–742
742–750
750–758
758–766
766–774
774–782
782–790
790–798
798–806
806–814
814–822
822–830
830–838
838–846
846–854
854–862
Table 8.6b. Analog Broadcast Nominal Frequencies for the
United Kingdom, Ireland, South Africa, Hong Kong, and
Western Europe.

PAL Overview 285
Table 8.7. Analog Cable TV Nominal Frequencies for the United Kingdom, Ireland, South Africa,
Hong Kong, and Western Europe.
Cable
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
Cable
Channel
Video
Carrier
(MHz)
Audio
Carrier
(MHz)
Channel
Range
(MHz)
E2
E3
E4
S01
S02
S03
S1
S2
S3
48.25
55.25
62.25
69.25
76.25
83.25
105.25
112.25
119.25
53.75
60.75
67.75
74.75
81.75
88.75
110.75
117.75
124.75
47–54
54–61
61–68
68–75
75–82
82–89
104–111
111–118
118–125
S11
S12
S13
S14
S15
S16
S17
S18
S19
231.25
238.25
245.25
252.25
259.25
266.25
273.25
280.25
287.25
236.75
243.75
250.75
257.75
264.75
271.75
278.75
285.75
292.75
230–237
237–244
244–251
251–258
258–265
265–272
272–279
279–286
286–293
S4
S5
S6
S7
S8
S9
S10
–
–
–
126.25
133.25
140.75
147.75
154.75
161.25
168.25
–
–
–
131.75
138.75
145.75
152.75
159.75
166.75
173.75
–
–
–
125–132
132–139
139–146
146–153
153–160
160–167
167–174
–
–
–
S20
S21
S22
S23
S24
S25
S26
S27
S28
S29
294.25
303.25
311.25
319.25
327.25
335.25
343.25
351.25
359.25
367.25
299.75
308.75
316.75
324.75
332.75
340.75
348.75
356.75
364.75
372.75
293–300
302–310
310–318
318–326
326–334
334–342
342–350
350–358
358–366
366–374
E5
E6
E7
E8
E9
E10
E11
E12
–
–
–
–
175.25
182.25
189.25
196.25
203.25
210.25
217.25
224.25
–
–
–
–
180.75
187.75
194.75
201.75
208.75
215.75
222.75
229.75
–
–
–
–
174–181
181–188
188–195
195–202
202–209
209–216
216–223
223–230
–
–
–
–
S30
S31
S32
S33
S34
S35
S36
S37
S38
S39
S40
S41
375.25
383.25
391.25
399.25
407.25
415.25
423.25
431.25
439.25
447.25
455.25
463.25
380.75
388.75
396.75
404.75
412.75
420.75
428.75
436.75
444.75
452.75
460.75
468.75
374–382
382–390
390–398
398–406
406–414
414–422
422–430
430–438
438–446
446–454
454–462
462–470

286 Chapter 8: NTSC, PAL, and SECAM Overview
Use by Country
Figure 8.19 shows the common designations
for PAL systems. The letters refer to the monochrome
standard for line and field rate, video
bandwidth (4.2, 5.0, 5.5, or 6.0 MHz), audio
carrier relative frequency, and RF channel
bandwidth (6.0, 7.0, or 8.0 MHz). The “PAL”
refers to the technique to add color information
to the monochrome signal. Detailed timing
parameters may be found in Table 8.9.
The following countries use the (I) PAL
standard.
Angola Malawi
Botswana Namibia
Gambia Nigeria
Guinea-Bissau South Africa
Hong Kong Tanzania
Ireland United Kingdom
Lesotho Zanzibar
Macau
The following countries use the (B) and
(G) PAL standards.
Albania Kenya
Algeria Kuwait
Austria Liberia
Bahrain Libya
Cambodia Lithuania
Cameroon Luxembourg
Croatia Malaysia
Cyprus Netherlands
Denmark New Zealand
Egypt Norway
Equatorial Guinea Oman
Ethiopia Pakistan
Finland Papua New Guinea
Germany Portugal
Iceland Qatar
Israel Sierra Leone
Italy Singapore
Jordan Slovenia
Somalia Syria
Spain Thailand
Sri Lanka Turkey
Sudan Yemen
Sweden Yugoslavia
Switzerland
The following countries use the (N) PAL
standard. Note that Argentina uses a modified
PAL standard, called “N C .”
Argentina Paraguay
Aryenuna Uruguay
The following countries use the (M) PAL
standard.
Brazil
The following countries use the (B) PAL
standard.
Australia Maldives
Bangladesh Malta
Belgium Nigeria
Brunei Darussalam Rwandese Republic
Ghana Sao Tome & Principe
India Seychelles
Indonesia Vanuatu
The following countries use the (G) PAL
standard.
Hungary Zambia
Mozambique Zimbabwe
Romania
The following countries use the (D) PAL
standard.
China Latvia
Czech Republic Poland
Hungary Romania
Korea, North

The following countries use the (H) PAL
standard.
Belgium
Luma Equation Derivation
The equation for generating luminance from
RGB information is determined by the chromaticities
of the three primary colors used by the
receiver and what color white actually is.
The chromaticities of the RGB primaries
and reference white (CIE illuminate D65 )are:
R: xr = 0.64 yr = 0.33 zr = 0.03
G: xg =0.29yg = 0.60 zg =0.11
B: xb =0.15yb = 0.06 zb =0.79
white: xw = 0.3127
zw = 0.3583
yw = 0.3290
where x and y are the specified CIE 1931 chromaticity
coordinates; z is calculated by knowingthatx+y+z=1.
As with NTSC, substituting the known values
gives us the solution for K r ,K g ,andK b :
Y is defined to be
or
Kr Kg Kb =
=
0.3127 ⁄ 0.3290
1
0.3583 ⁄ 0.3290
0.674
1.177
1.190
PAL Overview 287
0.64 0.29 0.15
0.33 0.60 0.06
0.03 0.11 0.79
Y=(K r y r )R´ +(K g y g )G´ +(K b y b )B´
= (0.674)(0.33)R´ + (1.177)(0.60)G´
+ (1.190)(0.06)B´
Y = 0.222R´ + 0.706G´ +0.071B´
However, the standard Y = 0.299R´ +
0.587G´ + 0.114B´ equation is still used. Adjustments
are made in the receiver to minimize
color errors.
– 1

288 Chapter 8: NTSC, PAL, and SECAM Overview
PALplus
PALplus (ITU-R BT.1197 and ETSI ETS
300731) is the result of a cooperative project
started in 1990, undertaken by several European
broadcasters. By 1995, they wanted to
provide an enhanced definition television system
(EDTV), compatible with existing receivers.
PALplus has been transmitted by a few
broadcasters since 1994.
A PALplus picture has a 16:9 aspect ratio.
On conventional TVs, it is displayed as a 16:9
letterboxed image with 430 active lines. On
PALplus TVs, it is displayed as a 16:9 picture
with 574 active lines, with extended vertical
resolution. The full video bandwidth is available
for luminance detail. Cross color artifacts
are reduced by clean encoding.
Wide Screen Signalling
Line 23 is contains a Widescreen Signalling
(WSS) control signal, defined by ITU-R
BT.1119 and ETSI EN 300294, used by PALplus
TVs. This signal indicates:
Program Aspect Ratio:
Full Format 4:3
Letterbox 14:9 Center
Letterbox 14:9 Top
Full Format 14:9 Center
Letterbox 16:9 Center
Letterbox 16:9 Top
Full Format 16:9 Anamorphic
Letterbox > 16:9 Center
Enhanced services:
Camera Mode
Film Mode
Subtitles:
Teletext Subtitles Present
Open Subtitles Present
PALplus is defined as being Letterbox 16:9
center, camera mode or film mode, helper signals
present using modulation, and clean
encoding used. Teletext subtitles may or may
not be present, and open subtitles may be
present only in the active picture area.
During a PALplus transmission, any active
video on lines 23 and 623 is blanked prior to
encoding. In addition to WSS data, line 23
includes 48 ±1 cycles of a 300 ±9 mV subcarrier
with a –U phase,starting51µs ±250 ns
after 0 H. Line 623 contains a 10 µs ±250 ns
white pulse, starting 20 µs ±250 ns after 0 H .
A PALplus TV has the option of deinterlacing
a Film Mode signal and displaying it on a
50-Hz progressive-scan display or using field
repeating on a 100-Hz interlaced display.
Ghost Cancellation
An optional ghost cancellation signal on line
318, defined by ITU-R BT.1124 and ETSI ETS
300732, allows a suitably adapted TV to measure
the ghost signal and cancel any ghosting
during the active video. A PALplus TV may or
may not support this feature.
Vertical Filtering
All PALplus sources start out as a 16:9 YCbCr
anamorphic image, occupying all 576 active
scan lines. Any active video on lines 23 and 623
is blanked prior to encoding (since these lines
are used for WSS and reference information),
resulting in 574 active lines per frame. Lines
24–310 and 336–622areusedforactivevideo.
Before transmission, the 574 active scan
lines of the 16:9 image are squeezed into 430
scan lines. To avoid aliasing problems, the vertical
resolution is reduced by lowpass filtering.
For Y, vertical filtering is done using a
Quadrature Mirror Filter (QMF) highpass and
lowpass pair. Using the QMF process allows
the highpass and lowpass information to be

esampled, transmitted, and later recombined
with minimal loss.
The Y QMF lowpass output is resampled
into three-quarters of the original height; little
information is lost to aliasing. After clean
encoding, it is the letterboxed signal that conventional
4:3 TVs display.
The Y QMF highpass output contains the
rest of the original vertical frequency. It is
used to generate the helper signals that are
transmitted using the “black” scan lines not
used by the letterbox picture.
Film Mode
A film mode broadcast has both fields of a
frame coming from the same image, as is usually
the case with a movie scanned on a telecine.
In film mode, the maximum vertical resolution
per frame is about 287 cycles per active
picture height (cph), limited by the 574 active
scan lines per frame.
The vertical resolution of Y is reduced to
215 cph so it can be transmitted using only 430
active lines. The QMF lowpass and highpass
filters split the Y vertical information into DC–
215 cph and 216–287 cph.
The Y lowpass information is re-scanned
into 430 lines to become the letterbox image.
Since the vertical frequency is limited to a
maximum of 215 cph, no information is lost.
The Y highpass output is decimated so
only one in four lines are transmitted. These
144 lines are used to transmit the helper signals.
Because of the QMF process, no information
is lost to decimation.
The72linesaboveand72linesbelowthe
central 430-line of the letterbox image are used
to transmit the 144 lines of the helper signal.
This results in a standard 574 active line picture,
but with the original image in its correct
aspect ratio, centered between the helper signals.
The scan lines containing the 300 mV
PAL Overview 289
helper signals are modulated using the U subcarrier
so they look black and are not visible to
the viewer.
After Fixed ColorPlus processing, the 574
scan lines are PAL encoded and transmitted as
a standard interlaced PAL frame.
Camera Mode
Camera (or video) mode assumes the fields of
a frame are independent of each other, as
would be the case when a camera scans a
scene in motion. Therefore, the image may
have changed between fields. Only intra-field
processing is done.
In camera mode, the maximum vertical
resolution per field is about 143 cycles per
active picture height (cph), limited by the 287
active scan lines per field.
The vertical resolution of Y is reduced to
107 cph so it can be transmitted using only 215
active lines. The QMF lowpass and highpass
filter pair split the Y vertical information into
DC–107 cph and 108–143 cph.
The Y lowpass information is re-scanned
into 215 lines to become the letterbox image.
Since the vertical frequency is limited to a
maximum of 107 cph, no information is lost.
The Y highpass output is decimated so
only one in four lines is transmitted. These 72
lines are used to transmit the helper signals.
Because of the QMF process, no information is
lost to decimation.
The36linesaboveand36linesbelowthe
central 215-line of the letterbox image are used
totransmitthe72linesofthehelpersignal.
This results in a 287 active line picture, but
with the original image in its correct aspect
ratio, centered between the helper signals. The
scan lines containing the 300 mV helper signals
are modulated using the U subcarrier so
they look black and are not visible to the
viewer.

290 Chapter 8: NTSC, PAL, and SECAM Overview
AftereitherFixedorMotionAdaptiveColorPlus
processing, the 287 scan lines are PAL
encoded and transmitted as a standard PAL
field.
Clean Encoding
Only the letterboxed portion of the PALplus
signal is clean encoded. The helper signals are
not actual PAL video. However, they are close
enough to video to pass through the transmission
path and remain fairly invisible on standard
TVs.
ColorPlus Processing
Fixed ColorPlus
Film Mode uses a Fixed ColorPlus technique,
making use of the lack of motion between the
two fields of the frame.
Fixed ColorPlus depends on the subcarrier
phase of the composite PAL signal being of
opposite phase when 312 lines apart. If these
two lines have the same luminance and
chrominance information, it can be separated
by adding and subtracting the composite signals
from each other. Adding cancels the
chrominance, leaving luminance. Subtracting
cancels the luminance, leaving chrominance.
In practice, Y information above 3 MHz
(Y HF ) is intra-frame averaged since it shares
the frequency spectrum with the modulated
chrominance. For line [n], Y HF is calculated as
follows:
0 ≤ n ≤ 214 for 430-line letterboxed image
YHF(60 + n) = 0.5(YHF(372 + n) +YHF(60 + n) )
Y HF(372 + n) =Y HF(60 + n)
Y HF is then added to the low-frequency Y
(Y LF ) information. The same intra-frame averaging
process is also used for Cb and Cr. The
430-line letterbox image is then PAL encoded.
Thus, Y information above 3 MHz, and
CbCr information, is the same on lines [n] and
[n+312]. Y information below 3 MHz may be
different on lines [n] and [n+312]. The full vertical
resolution of 287 cph is reconstructed by
the decoder with the aid of the helper signals.
Motion Adaptive ColorPlus (MACP)
Camera Mode uses either Motion Adaptive
ColorPlus or Fixed ColorPlus, depending on
the amount of motion between fields. This
requires a motion detector in both the encoder
and decoder.
To detect movement, the CbCr data on
lines [n] and [n+312] are compared. If they
match, no movement is assumed, and Fixed
ColorPlus operation is used. If the CbCr data
doesn’t match, movement is assumed, and
Motion Adaptive ColorPlus operation is used.
During Motion Adaptive ColorPlus operation,
the amount of Y HF added to Y LF is dependent
on the difference between CbCr (n) and
CbCr (n + 312) . For the maximum CbCr difference,
no Y HF data for lines [n] and [n+312] is
transmitted.
In addition, the amount of intra-frame averaged
CbCr data mixed with the direct CbCr
data is dependent on the difference between
CbCr (n) and CbCr (n + 312) .Forthemaximum
CbCr difference, only direct CbCr data is transmitted
separately for lines [n] and [n+312].

SECAM Overview
SECAM (Sequentiel Couleur Avec Mémoire or
Sequential Color with Memory) was developed
in France, with broadcasting starting in 1967,
by realizing that, if color could be bandwidthlimited
horizontally, why not also vertically?
The two pieces of color information (Db and
Dr) added to the monochrome signal could be
transmitted on alternate lines, avoiding the
possibility of crosstalk.
The receiver requires memory to store
one line so that it is concurrent with the next
line, and also requires the addition of a lineswitching
identification technique.
Like PAL, SECAM is a 625-line, 50-fieldper-second,
2:1 interlaced system. SECAM was
adopted by other countries; however, many are
changing to PAL due to the abundance of professional
and consumer PAL equipment.
Luminance Information
The monochrome luminance (Y) signal is
derived from R´G´B´:
Y = 0.299R´ + 0.587G´ + 0.114B´
As with NTSC and PAL, the luminance signal
occupies the entire video bandwidth.
SECAM has several variations, depending on
the video bandwidth and placement of the
audio subcarrier. The video signal has a bandwidth
of 5.0 or 6.0 MHz, depending on the specific
SECAM standard.
Color Information
SECAM transmits Db information during one
line and Dr information during the next line;
luminance information is transmitted each
SECAM Overview 291
line. Db and Dr are scaled versions of B´ –Y
and R´–Y:
Dr = –1.902(R´–Y)
Db = 1.505(B´ –Y)
Since there is an odd number of lines, any
given line contains Db information on one field
and Dr information on the next field. The
decoder requires a 1-H delay, switched synchronously
with the Db and Dr switching, so
that Db and Dr exist simultaneously in order to
convert to YCbCr or RGB.
Color Modulation
SECAM uses FM modulation to transmit the
Db and Dr color difference information, with
each component having its own subcarrier.
Db and Dr are lowpass filtered to 1.3 MHz
andpre-emphasisisapplied.Thecurveforthe
pre-emphasis is expressed by:
f
1 + j⎛-----
⎞
⎝85⎠ A =
------------------------f
1 + j⎛--------⎞
⎝255⎠ where ƒ = signal frequency in kHz.
Afterpre-emphasis,DbandDrfrequency
modulate their respective subcarriers. The frequency
of each subcarrier is defined as:
FOB = 272 FH = 4.250000 MHz (± 2kHz)
FOR = 282 FH = 4.406250 MHz (± 2kHz)
These frequencies represent no color
information. Nominal Dr deviation is ±280 kHz
and the nominal Db deviation is ±230 kHz. Figure
8.23 illustrates the frequency modulation

292 Chapter 8: NTSC, PAL, and SECAM Overview
process of the color difference signals. The
choice of frequency shifts reflects the idea of
keeping the frequencies representing critical
colors away from the upper limit of the spectrum
to minimize distortion.
After modulation of Db and Dr, subcarrier
pre-emphasis is applied, changing the amplitude
of the subcarrier as a function of the frequency
deviation. The intention is to reduce
the visibility of the subcarriers in areas of low
luminance and to improve the signal-to-noise
ratio of highly saturated colors. This preemphasis
is given as:
1 j16F
G M +
= -------------------------
1 + j1.26F
whereF=(ƒ/4286) – (4286/ƒ), ƒ = instantaneous
subcarrier frequency in kHz, and 2M =
23 ± 2.5% of luminance amplitude.
Y
EVEN LINES
ODD LINES
YELLOW
– DB
RED
+ DR
GRAY
FOB
4.25
As shown in Table 8.8 and Figure 8.24, Db
and Dr information is transmitted on alternate
scan lines. The phase of the subcarriers is also
reversed 180° on every third line and between
each field to further reduce subcarrier visibility.
Note that subcarrier phase information in
the SECAM system carries no picture information.
Composite Video Generation
The subcarrier data is added to the luminance
along with appropriate horizontal and vertical
sync signals, blanking signals, and burst signals
to generate composite video.
As with PAL, SECAM requires some
means of identifying the line-switching
sequence. Modern practice has been to use a
F OR /F OB burst after most horizontal syncs to
derive the switching synchronization information,
as shown in Figure 8.25.
GRAY
FOR
4.40
BLUE
+ DB
CYAN
– DR
Figure 8.23. SECAM FM Color Modulation.
6
MHZ

Use by Country
Figure8.26showsthecommondesignations
for SECAM systems. The letters refer to the
monochrome standard for line and field rates,
video bandwidth (5.0 or 6.0 MHz), audio carrier
relative frequency, and RF channel bandwidth.
The SECAM refers to the technique to
add color information to the monochrome signal.
Detailed timing parameters may be found
in Table 8.9.
The following countries use the (B) and
(G) SECAM standards.
Greece Mauritius
Iran Morocco
Iraq Saudi Arabia
Lebanon Tunisia
Mali
Table 8.8. SECAM Color Versus Line and Field Timing.
SECAM Overview 293
Field
Line
Number
Color Subcarrier Phase
odd N Dr 0°
even N + 313 Db 180°
odd N + 1 Db 0°
even N + 314 Dr 0°
odd N + 2 Dr 180°
even N + 315 Db 180°
odd N + 3 Db 0°
even N + 316 Dr 180°
odd N + 4 Dr 0°
even N + 317 Db 0°
odd N + 5 Db 180°
even N + 318 Dr 180°
The following countries use the (D) and
(K) SECAM standards.
Azerbaijan Latvia
Belarus Lithuania
Bulgaria Moldova
Estonia Russia
Georgia Ukraine
Kazakhstan Viet Nam
The following countries use the (B)
SECAM standard.
Mauritania Djibouti
The following countries use the (D)
SECAM standard.
Afghanistan Mongolia

294 Chapter 8: NTSC, PAL, and SECAM Overview
DR DB
START
OF
VSYNC
620 621 622 623 624 625 1 2 3 4 5 6 7 23 24
DB
ANALOG
FIELD 1
ANALOG
FIELD 2
308 309 310 311 312 313 314 315 316 317 318 319 320 336 337
DB DR
DR DB
ANALOG
FIELD 3
620 621 622 623 624 625 1 2 3 4 5 6 7 23 24
DR
DR DB
DB DR
DB DR
ANALOG
FIELD 4
DR DB
DB DR
DB DR
DR DB
308 309 310 311 312 313 314 315 316 317 318 319 320 336 337
Figure 8.24. Four-field SECAM Sequence. See Figure 8.5 for equalization and serration pulse
details.
FO
HORIZONTAL
BLANKING
BLANK LEVEL
SYNC LEVEL
Figure 8.25. SECAM Chroma Synchronization Signals.

FREQUENCY MODULATED SUBCARRIERS
FOR = 282 FH
FOB = 272 FH
LINE SEQUENTIAL DR AND DB SIGNALS
"D, K, K1, L"
LINE / FIELD = 625 / 50
FH = 15.625 KHZ
FV = 50 HZ
BLANKING SETUP = 0 IRE
VIDEO BANDWIDTH = 6.0 MHZ
AUDIO CARRIER = 6.5 MHZ
CHANNEL BANDWIDTH = 8 MHZ
The following countries use the (K1)
SECAM standard.
Benin Gabon
Burkina Faso Guadeloupe
Burundi Madagascar
Cape Verde Niger
Central African Senegal
Republic Tahiti
Chad Togo
Comoros Zaire
Congo
"B, G"
LINE / FIELD = 625 / 50
FH = 15.625 KHZ
FV = 50 HZ
BLANKING SETUP = 0 IRE
VIDEO BANDWIDTH = 5.0 MHZ
AUDIO CARRIER = 5.5 MHZ
CHANNEL BANDWIDTH:
B = 7 MHZ
G = 8 MHZ
Figure 8.26. Common SECAM Systems.
SECAM Overview 295
The following countries use the (L)
SECAM standard.
France Monaco

296 Chapter 8: NTSC, PAL, and SECAM Overview
Luminance Equation Derivation
The equation for generating luminance from
RGB information is determined by the chromaticities
of the three primary colors used by the
receiver and what color white actually is.
The chromaticities of the RGB primaries
and reference white (CIE illuminate D 65 )are:
R: xr =0.64 yr = 0.33 zr = 0.03
G: xg = 0.29 yg =0.60zg =0.11
B: xb = 0.15 yb =0.06zb =0.79
white: xw = 0.3127
zw = 0.3583
yw = 0.3290
where x and y are the specified CIE 1931 chromaticity
coordinates; z is calculated by knowing
that x + y + z = 1. Once again, substituting
theknownvaluesgivesusthesolutionforK r ,
K g ,andK b :
Y is defined to be
or
Kr Kg Kb =
=
0.3127 ⁄ 0.3290
1
0.3583 ⁄ 0.3290
0.674
1.177
1.190
0.64 0.29 0.15
0.33 0.60 0.06
0.03 0.11 0.79
Y=(K r y r )R´ +(K g y g )G´ +(K b y b )B´
= (0.674)(0.33)R´ + (1.177)(0.60)G´
+ (1.190)(0.06)B´
Y = 0.222R´ + 0.706G´ +0.071B´
However, the standard Y = 0.299R´ +
0.587G´ + 0.114B´ equation is still used. Adjustments
are made in the receiver to minimize
color errors.
– 1

SCAN LINES PER FRAME
FIELD FREQUENCY
(FIELDS / SECOND)
LINE FREQUENCY (HZ)
PEAK WHITE LEVEL (IRE)
SYNC TIP LEVEL (IRE)
SETUP (IRE)
PEAK VIDEO LEVEL (IRE)
GAMMA OF RECEIVER
VIDEO BANDWIDTH (MHZ)
LUMINANCE SIGNAL
M
525
59.94
15,734
100
–40
7.5 ± 2.5
120
2.2
4.2
N
625
50
15,625
100
–40 (–43)
7.5 ± 2.5 (0)
2.8
5.0 (4.2)
1 Values in parentheses apply to (NC) PAL used in Argentina.
625
50
15,625
100
–43
Y = 0.299R´ + 0.685G´ + 0.114B´ (RGB ARE GAMMA–CORRECTED)
0
SECAM Overview 297
B, G H I D, K K1
L
133
2.8
5.0
Table 8.9a. Basic Characteristics of Color Video Signals.
2.8
5.0
133
2.8
5.5
115
2.8
6.0
115
2.8
6.0
125
2.8
6.0

298 Chapter 8: NTSC, PAL, and SECAM Overview
Characteristics M N
Notes
1. 0 H is at 50% point of falling edge of horizontal sync.
2. In case of different standards having different specifications and tolerances, the
tightest specification and tolerance is listed.
3. Timing is measured between half-amplitude points on appropriate signal edges.
Table 8.9b. Details of Line Synchronization Signals.
B, D, G, H, I
K,K1,L,N C
Nominal line period (µs) 63.5555 64 64
Line blanking interval (µs) 10.7 ± 0.1 10.88 ± 0.64 11.85 ± 0.15
0 H to start of active video (µs) 9.2 ± 0.1 9.6 ± 0.64 10.5
Front porch (µs) 1.5 ± 0.1 1.92 ± 0.64 1.65 ± 0.15
Line synchronizing pulse (µs) 4.7 ± 0.1 4.99 ± 0.77 4.7 ± 0.2
Rise and fall time of line
blanking (10%, 90%) (ns) 140 ± 20 300 ± 100 300 ± 100
Rise and fall time of line
synchronizing pulses (10%, 90%) (ns) 140 ± 20 ≤ 250 250 ± 50

Characteristics M N
Notes
1. In case of different standards having different specifications and tolerances, the tightest
specification and tolerance is listed.
2. Timing is measured between half-amplitude points on appropriate signal edges.
Table 8.9c. Details of Field Synchronization Signals.
SECAM Overview 299
B, D, G, H, I
K,K1,L,N C
Field period (ms) 16.6833 20 20
Field blanking interval 20 lines 19–25 lines 25 lines
Rise and fall time of field blanking
(10%, 90%) (ns)
Duration of equalizing and
synchronizing sequences
140 ± 20 ≤ 250 300 ± 100
3H 3H 2.5H
Equalizing pulse width (µs) 2.3 ± 0.1 2.43 ± 0.13 2.35 ± 0.1
Serration pulse width (µs) 4.7 ± 0.1 4.7 ± 0.8 4.7 ± 0.1
Rise and fall time of synchronizing and
equalizing pulses (10%, 90%) (ns)
140 ± 20 < 250 250 ± 50

300 Chapter 8: NTSC, PAL, and SECAM Overview
ATTENUATION OF COLOR
DIFFERENCE SIGNALS
START OF BURST
AFTER 0H (µS)
BURST DURATION (CYCLES)
BURST PEAK AMPLITUDE
Video Test Signals
M / NTSC
U, V, I, Q:
< 2 DB AT 1.3 MHZ
> 20 DB AT 3.6 MHZ
OR Q:
< 2 DB AT 0.4 MHZ
< 6 DB AT 0.5 MHZ
> 6 DB AT 0.6 MHZ
5.3 ± 0.07
9 ± 1
40 ± 1 IRE
Many industry-standard video test signals
have been defined to help test the relative quality
of encoding, decoding, and the transmission
path, and to perform calibration. Note that
some video test signals cannot be properly
generated by providing RGB data to an
encoder; in this case, YCbCr data may be used.
If the video standard uses a 7.5-IRE setup,
typically only test signals used for visual examination
use the 7.5-IRE setup. Test signals
designed for measurement purposes typically
use a 0-IRE setup, providing the advantage of
defining a known blanking level.
Color Bars Overview
Color bars are one of the standard video test
signals, and there are several variations,
depending on the video standard and application.
For this reason, this section reviews the
M / PAL
< 2 DB AT 1.3 MHZ
> 20 DB AT 3.6 MHZ
5.8 ± 0.1
9 ± 1
42.86 ± 4 IRE
Note: Values in parentheses apply to (N C) PALusedinArgentina.
B, D, G, H, I, N / PAL
< 3 DB AT 1.3 MHZ
> 20 DB AT 4 MHZ
(> 20 DB AT 3.6 MHZ)
5.6 ± 0.1
10 ± 1 (9 ± 1)
42.86 ± 4 IRE
Table 8.9d. Basic Characteristics of Color Video Signals.
B, D, G, K, K1, K / SECAM
< 3 DB AT 1.3 MHZ
> 30 DB AT 3.5 MHZ
(BEFORE LOW FREQUENCY
PRE–CORRECTION)
most common color bar formats. Color bars
have two major characteristics: amplitude and
saturation.
The amplitude of a color bar signal is
determined by:
amplitude (%)
where max(R,G,B) a is the maximum value of
R´G´B´ during colored bars and max(R,G,B) b
is the maximum value of R´G´B´ during reference
white.
The saturation of a color bar signal is less
than 100% if the minimum value of any one of
the R´G´B´ components is not zero. The saturation
is determined by:
saturation (%) =
=
min( R, G, B)
1 ⎛-------------------------------- ⎞
⎝max( R, G, B)
⎠
γ
–
max (R, G, B)
------------------------------------------------- a × 100
max (R, G, B) b
× 100

where min(R,G,B) and max(R,G,B) are the
minimum and maximum values, respectively,
of R´G´B´ during colored bars, and γ is the
gamma exponent, typically [1/0.45].
NTSC Color Bars
In 1953, it was normal practice for the analog
R´G´B´ signals to have a 7.5 IRE setup, and the
original NTSC equations assumed this form of
input to an encoder. Today, digital R´G´B´ or
YCbCr signals typically do not include the 7.5
IRE setup, and the 7.5 IRE setup is added
within the encoder.
The different color bar signals are
described by four amplitudes, expressed in
percent, separated by oblique strokes. 100%
saturation is implied, so saturation is not specified.
The first and second numbers are the
white and black amplitudes, respectively. The
third and fourth numbers are the white and
black amplitudes from which the color bars are
derived.
For example, 100/7.5/75/7.5 color bars
would be 75% color bars with 7.5% setup in
which the white bar has been set to 100% and
the black bar to 7.5%. Since NTSC systems usually
have the 7.5% setup, the two common color
bars are 75/7.5/75/7.5 and 100/7.5/100/7.5,
which are usually shortened to 75% and 100%,
respectively. The 75% bars are most commonly
used. Television transmitters do not pass information
with an amplitude greater than about
120 IRE. Therefore, the 75% color bars are
used for transmission testing. The 100% color
bars may be used for testing in situations
where a direct connection between equipment
is possible. The 75/7.5/75/7.5 color bars are a
part of the Electronic Industries Association
EIA-189-A Encoded Color Bar Standard.
Figure 8.27 shows a typical vectorscope
display for full-screen 75% NTSC color bars.
Figure8.28illustratesthevideowaveformfor
75% color bars.
Video Test Signals 301
Tables 8.10 and 8.11 list the luminance and
chrominance levels for the two common color
barformatsforNTSC.
For reference, the RGB and YCbCr values
to generate the standard NTSC color bars are
shown in Tables 8.12 and 8.13. RGB is
assumed to have a range of 0–255; YCbCr is
assumed to have a range of 16–235 for Y and
16–240 for Cb and Cr. It is assumed any 7.5 IRE
setup is implemented within the encoder.
PAL Color Bars
Unlike NTSC, PAL does not support a 7.5 IRE
setup; the black and blank levels are the same.
The different color bar signals are usually
described by four amplitudes, expressed in
percent, separated by oblique strokes. The
first and second numbers are the maximum
and minimum percentages, respectively, of
R´G´B´ values for an uncolored bar. The third
and fourth numbers are the maximum and
minimum percentages, respectively, of R´G´B´
values for a colored bar.
Since PAL systems have a 0% setup, the
two common color bars are 100/0/75/0 and
100/0/100/0, which are usually shortened to
75% and 100%, respectively. The 75% color bars
are used for transmission testing. The 100%
color bars may be used for testing in situations
where a direct connection between equipment
is possible.
The 100/0/75/0 color bars also are
referred to as EBU (European Broadcast
Union) color bars. All of the color bars discussed
in this section are also a part of Specification
of Television Standards for 625-line
System-I Transmissions (1971) published by the
Independent Television Authority (ITA) and
the British Broadcasting Corporation (BBC),
and ITU-R BT.471.

302 Chapter 8: NTSC, PAL, and SECAM Overview
Figure 8.27. Typical Vectorscope Display for 75% NTSC Color Bars.

100 IRE
40 IRE
20 IRE
20 IRE
7.5 IRE
3.58 MHZ
COLOR BURST
(9 CYCLES)
WHITE
+ 77
YELLOW
+ 69
+ 38
CYAN
+ 100
Figure 8.28. IRE Values for 75% NTSC Color Bars.
Luminance
(IRE)
Chrominance
Level
(IRE)
+ 56
+ 12
GREEN
+ 89
+ 48
+ 7
Minimum
Chrominance
Excursion
(IRE)
Table 8.10. 75/7.5/75/7.5 (75%) NTSC Color Bars.
MAGENTA
+ 77
+ 36
– 5
RED
+ 72
+ 28
– 16
BLUE
+ 46
+ 15
– 16
BLACK
Maximum
Chrominance
Excursion
(IRE)
Video Test Signals 303
WHITE LEVEL (100 IRE)
BLACK LEVEL (7.5 IRE)
BLANK LEVEL (0 IRE)
SYNC LEVEL (– 40 IRE)
Chrominance
Phase
(degrees)
white 76.9 0 – – –
yellow 69.0 62.1 37.9 100.0 167.1
cyan 56.1 87.7 12.3 100.0 283.5
green 48.2 81.9 7.3 89.2 240.7
magenta 36.2 81.9 –4.8 77.1 60.7
red 28.2 87.7 –15.6 72.1 103.5
blue 15.4 62.1 –15.6 46.4 347.1
black 7.5 0 – – –

304 Chapter 8: NTSC, PAL, and SECAM Overview
Luminance
(IRE)
Chrominance
Level
(IRE)
Minimum
Chrominance
Excursion
(IRE)
Maximum
Chrominance
Excursion
(IRE)
Table 8.11. 100/7.5/100/7.5 (100%) NTSC Color Bars.
Chrominance
Phase
(degrees)
white 100.0 0 – – –
yellow 89.5 82.8 48.1 130.8 167.1
cyan 72.3 117.0 13.9 130.8 283.5
green 61.8 109.2 7.2 116.4 240.7
magenta 45.7 109.2 –8.9 100.3 60.7
red 35.2 117.0 –23.3 93.6 103.5
blue 18.0 82.8 –23.3 59.4 347.1
black 7.5 0 – – –
White
Yellow
Cyan
Green
gamma-corrected RGB (gamma = 1/0.45)
R´ 191 191 0 0 191 191 0 0
G´ 191 191 191 191 0 0 0 0
B´ 191 0 191 0
linear RGB
191 0 191 0
R 135 135 0 0 135 135 0 0
G 135 135 135 135 0 0 0 0
B 135 0 135 0
YCbCr
135 0 135 0
Y 180 162 131 112 84 65 35 16
Cb 128 44 156 72 184 100 212 128
Cr 128 142 44 58 198 212 114 128
Table 8.12. RGB and YCbCr Values for 75% NTSC Color Bars.
Magenta
Red
Blue
Black

White
Yellow
Cyan
Green
gamma-corrected RGB (gamma = 1/0.45)
R´ 255 255 0 0 255 255 0 0
G´ 255 255 255 255 0 0 0 0
B´ 255 0 255 0
linear RGB
255 0 255 0
R 255 255 0 0 255 255 0 0
G 255 255 255 255 0 0 0 0
B 255 0 255 0
YCbCr
255 0 255 0
Y 235 210 170 145 106 81 41 16
Cb 128 16 166 54 202 90 240 128
Cr 128 146 16 34 222 240 110 128
Table 8.13. RGB and YCbCr Values for 100% NTSC Color Bars.
Figure8.29illustratesthevideowaveform
for 75% color bars. Figure 8.30 shows a typical
vectorscope display for full-screen 75% PAL
color bars.
Tables 8.14, 8.15, and 8.16 list the luminance
and chrominance levels for the three
common color bar formats for PAL.
For reference, the RGB and YCbCr values
to generate the standard PAL color bars are
shown in Tables 8.17, 8.18, and 8.19. RGB is
assumed to have a range of 0–255; YCbCr is
assumed to have a range of 16–235 for Y and
16–240 for Cb and Cr.
Magenta
Red
Blue
EIA Color Bars (NTSC)
Video Test Signals 305
Black
The EIA color bars (Figure 8.28 and Table
8.10) are a part of the EIA-189-A standard. The
seven bars (gray, yellow, cyan, green, magenta,
red, and blue) are at 75% amplitude, 100% saturation.
The duration of each color bar is 1/7 of
the active portion of the scan line. Note that
theblackbarinFigure8.28andTable8.10is
not part of the standard and is shown for reference
only. The color bar test signal allows
checking for hue and color saturation accuracy.

306 Chapter 8: NTSC, PAL, and SECAM Overview
Luminance
(volts)
Peak-to-Peak Chrominance
U axis
(volts)
V axis
(volts)
Total
(volts)
Line n
(135° burst)
Table 8.14. 100/0/75/0 (75%) PAL Color Bars.
Chrominance
Phase
(degrees)
Line n + 1
(225° burst)
white 0.700 0 – – – –
yellow 0.465 0.459 0.105 0.470 167 193
cyan 0.368 0.155 0.646 0.664 283.5 76.5
green 0.308 0.304 0.541 0.620 240.5 119.5
magenta 0.217 0.304 0.541 0.620 60.5 299.5
red 0.157 0.155 0.646 0.664 103.5 256.5
blue 0.060 0.459 0.105 0.470 347 13.0
black 0 0 0 0 – –
Luminance
(volts)
Peak-to-Peak Chrominance
U axis
(volts)
V axis
(volts)
Total
(volts)
Line n
(135° burst)
Table 8.15. 100/0/100/0 (100%) PAL Color Bars.
Chrominance
Phase
(degrees)
Line n + 1
(225° burst)
white 0.700 0 – – – –
yellow 0.620 0.612 0.140 0.627 167 193
cyan 0.491 0.206 0.861 0.885 283.5 76.5
green 0.411 0.405 0.721 0.827 240.5 119.5
magenta 0.289 0.405 0.721 0.827 60.5 299.5
red 0.209 0.206 0.861 0.885 103.5 256.5
blue 0.080 0.612 0.140 0.627 347 13.0
black 0 0 0 0 – –

100 IRE
43 IRE
21.43 IRE
21.43 IRE
Luminance
(volts)
4.43 MHZ
COLOR BURST
(10 CYCLES)
Peak-to-Peak Chrominance
U axis
(volts)
WHITE
V axis
(volts)
YELLOW
+ 100
+ 66
+ 32
CYAN
+ 53
+ 6
Total
(volts)
Table 8.16. 100/0/100/25 (98%) PAL Color Bars.
GREEN
+ 88
+ 44
0
MAGENTA
+ 75
+ 31
– 13
RED
+ 69
+ 22
Line n
(135° burst)
BLUE
+ 43
+ 9
– 25 – 25
BLACK
Video Test Signals 307
Chrominance
Phase
(degrees)
Line n + 1
(225° burst)
white 0.700 0 – – – –
yellow 0.640 0.459 0.105 0.470 167 193
cyan 0.543 0.155 0.646 0.664 283.5 76.5
green 0.483 0.304 0.541 0.620 240.5 119.5
magenta 0.392 0.304 0.541 0.620 60.5 299.5
red 0.332 0.155 0.646 0.664 103.5 256.5
blue 0.235 0.459 0.105 0.470 347 13.0
black 0 0 0 0 – –
Figure 8.29. IRE Values for 75% PAL Color Bars.
WHITE LEVEL (100 IRE)
BLACK / BLANK LEVEL (0 IRE)
SYNC LEVEL (– 43 IRE)

308 Chapter 8: NTSC, PAL, and SECAM Overview
Figure 8.30. Typical Vectorscope Display for 75% PAL Color Bars.

White
Yellow
Cyan
Green
gamma-corrected RGB (gamma = 1/0.45)
R´ 255 191 0 0 191 191 0 0
G´ 255 191 191 191 0 0 0 0
B´ 255 0 191 0
linear RGB
191 0 191 0
R 255 135 0 0 135 135 0 0
G 255 135 135 135 0 0 0 0
B 255 0 135 0
YCbCr
135 0 135 0
Y 235 162 131 112 84 65 35 16
Cb 128 44 156 72 184 100 212 128
Cr 128 142 44 58 198 212 114 128
Table 8.17. RGB and YCbCr Values for 75% PAL Color Bars.
White
Yellow
Cyan
Green
gamma-corrected RGB (gamma = 1/0.45)
R´ 255 255 0 0 255 255 0 0
G´ 255 255 255 255 0 0 0 0
B´ 255 0 255 0
linear RGB
255 0 255 0
R 255 255 0 0 255 255 0 0
G 255 255 255 255 0 0 0 0
B 255 0 255 0
YCbCr
255 0 255 0
Y 235 210 170 145 106 81 41 16
Cb 128 16 166 54 202 90 240 128
Cr 128 146 16 34 222 240 110 128
Table 8.18. RGB and YCbCr Values for 100% PAL Color Bars.
Magenta
Magenta
Red
Red
Blue
Blue
Video Test Signals 309
Black
Black

310 Chapter 8: NTSC, PAL, and SECAM Overview
EBU Color Bars (PAL)
The EBU color bars are similar to the EIA
color bars, except a 100 IRE white level is used
(see Figure 8.29 and Table 8.14). The six colored
bars (yellow, cyan, green, magenta, red,
and blue) are at 75% amplitude, 100% saturation,
while the white bar is at 100% amplitude.
The duration of each color bar is 1/7 of the
active portion of the scan line. Note that the
black bar in Figure 8.29 and Table 8.14 is not
part of the standard and is shown for reference
only. The color bar test signal allows checking
for hue and color saturation accuracy.
SMPTE Bars (NTSC)
White
Yellow
Cyan
Table 8.19. RGB and YCbCr Values for 98% PAL Color Bars.
This split-field test signal is composed of the
EIA color bars for the first 2/3 of the field, the
Reverse Blue bars for the next 1/12 of the
Green
gamma-corrected RGB (gamma = 1/0.45)
R´ 255 255 44 44 255 255 44 44
G´ 255 255 255 255 44 44 44 44
B´ 255 44 255 44
linear RGB
255 44 255 44
R 255 255 5 5 255 255 5 5
G 255 255 255 255 5 5 5 5
B 255 5 255 5
YCbCr
255 5 255 5
Y 235 216 186 167 139 120 90 16
Cb 128 44 156 72 184 100 212 128
Cr 128 142 44 58 198 212 114 128
Magenta
Red
Blue
field, and the PLUGE test signal for the
remainder of the field.
Reverse Blue Bars
Black
The Reverse Blue bars are composed of the
blue, magenta, and cyan colors bars from the
EIA/EBU color bars, but are arranged in a different
order—blue, black, magenta, black,
cyan, black, and white. The duration of each
color bar is 1/7 of the active portion of the scan
line. Typically, Reverse Blue bars are used with
the EIA or EBU color bar signal in a split-field
arrangement, with the EIA/EBU color bars
comprising the first 3/4 of the field and the
Reverse Blue bars comprising the remainder
of the field. This split-field arrangement eases
adjustment of chrominance and hue on a color
monitor.

PLUGE
PLUGE (Picture Line-Up Generating Equipment)
is a visual black reference, with one area
blacker-than-black, one area at black, and one
area lighter-than-black. The brightness of the
monitor is adjusted so that the black and
blacker-than-black areas are indistinguishable
from each other and the lighter-than-black area
is slightly lighter (the contrast should be at the
normal setting). Additional test signals, such
as a white pulse and modulated IQ signals are
usually added to facilitate testing and monitor
alignment.
3.58 MHZ
COLOR BURST
(9 CYCLES)
+ 20
– 20
– I
WHITE
+ 100
+ Q
+ 27.5 + 27.5
– 12.5 – 12.5
+ 3.5
+ 11.5
MICROSECONDS = 9.7 19.1 28.5 38 47 49.6 52 54.5
BLACK LEVEL (7.5 IRE)
BLANK LEVEL (0 IRE)
SYNC LEVEL (– 40 IRE)
Video Test Signals 311
The NTSC PLUGE test signal (shown in
Figure 8.31) is composed of a 7.5 IRE (black
level) pedestal with a 40 IRE “–I” phase modulation,
a 100 IRE white pulse, a 40 IRE “+Q”
phase modulation, and 3.5 IRE, 7.5 IRE, and
11.5 IRE pedestals. Typically, PLUGE is used
as part of the SMPTE bars.
For PAL, each country has its own slightly
different PLUGE configuration, with most differences
being the black pedestal level used,
and work is being done on a standard test signal.
Figure 8.32 illustrates a typical PAL
PLUGE test signal. Usually used as a fullscreen
test signal, it is composed of a 0 IRE
Figure 8.31. PLUGE Test Signal for NTSC. IRE values are indicated.

312 Chapter 8: NTSC, PAL, and SECAM Overview
pedestal with PLUGE (–2 IRE,0IRE,and2
IRE pedestals) and a white pulse. The white
pulse may have five levels of brightness (0, 25,
50, 75, and 100 IRE), depending on the scan
line number, as shown in Figure 8.32. The
PLUGE is displayed on scan lines that have
non-zero IRE white pulses. ITU-R BT.1221 discusses
considerations for various PAL systems.
4.43 MHZ
COLOR BURST
(10 CYCLES)
+ 21.43
– 21.43
– 2
+ 2
Y Bars
WHITE LEVEL (IRE)
+ 100
MICROSECONDS = 22.5 24.8 27.1 29.4 41 52.6
The Y bars consist of the luminance-only levels
of the EIA/EBU color bars; however, the black
level (7.5 IRE for NTSC and 0 IRE for PAL) is
included and the color burst is still present.
The duration of each luminance bar is therefore
1/8 of the active portion of the scan line. Y
bars are useful for color monitor adjustment
and measuring luminance nonlinearity. Typically,
the Y bars signal is used with the EIA or
EBU color bar signal in a split-field arrangement,
with the EIA/EBU color bars comprising
the first 3/4 of the field and the Y bars
signal comprising the remainder of the field.
+ 75
+ 50
+ 25
0
FULL DISPLAY
LINE NUMBERS
63 / 375
115 / 427
167 / 479
219 / 531
271 / 583
BLANK / BLACK LEVEL (0 IRE)
SYNC LEVEL (– 43 IRE)
Figure 8.32. PLUGE Test Signal for PAL. IRE values are indicated.

Red Field
The Red Field signal consists of a 75% amplitude,
100% saturation red chrominance signal.
This is useful as the human eye is sensitive to
static noise intermixed in a red field. Distortions
that cause small errors in picture quality
canbeexaminedvisuallyfortheeffectonthe
picture. Typically, the Red Field signal is used
with the EIA/EBU color bars signal in a splitfield
arrangement, with the EIA/EBU color
bars comprising the first 3/4 of the field, and
the Red Field signal comprising the remainder
of the field.
10-Step Staircase
This test signal is composed of ten unmodulated
luminance steps of 10 IRE each, ranging
from0IREto100IRE,showninFigure8.33.
Thistestsignalmaybeusedtomeasureluminance
nonlinearity.
COLOR BURST
10
IRE
LEVELS
20
30
40
50
60
Modulated Ramp
MICROSECONDS = 17.5 21.5 25.5 29.5 33.5 37.5 41.5 45.5 49.5 53.5 61.8
70
80
90
100
Video Test Signals 313
The modulated ramp test signal, shown in Figure
8.34, is composed of a luminance ramp
from 0 IRE to either 80 or 100 IRE, superimposed
with modulated chrominance that has a
phase of 0° ±1° relative to the burst. The 80
IRE ramp provides testing of the normal operating
range of the system; a 100 IRE ramp may
be used to optionally test the entire operating
range. The peak-to-peak modulated chrominance
is 40 ±0.5 IRE for (M) NTSC and 42.86
±0.5 IRE for (B, D, G, H, I) PAL. Note a 0 IRE
setup is used. The rise and fall times at the
start and end of the modulated ramp envelope
are 400 ±25 ns (NTSC systems) or approximately
1 µs (PAL systems). This test signal
maybeusedtomeasuredifferentialgain.The
modulated ramp signal is preferred over a 5step
or 10-step modulated staircase signal
when testing digital systems.
WHITE LEVEL (100 IRE)
BLANK LEVEL (0 IRE)
SYNC LEVEL
Figure 8.33. Ten-Step Staircase Test Signal for NTSC and PAL.

314 Chapter 8: NTSC, PAL, and SECAM Overview
Modulated Staircase
The 5-step modulated staircase signal (a 10step
version is also used), shown in Figure
8.35, consists of 5 luminance steps, superimposed
with modulated chrominance that has a
phase of 0° ±1° relative to the burst. The peakto-peak
modulated chrominance amplitude is
40 ±0.5 IRE for (M) NTSC and 42.86 ±0.5 IRE
for (B, D, G, H, I) PAL. Note a 0 IRE setup is
used. The rise and fall times of each modulation
packet envelope are 400 ±25 ns (NTSC
systems) or approximately 1 µs (PAL systems).
The luminance IRE levels for the 5-step
modulatedstaircasesignalareshowninFigure
8.35. This test signal may be used to measure
differential gain. The modulated ramp
signal is preferred over a 5-step or 10-step
modulated staircase signal when testing digital
systems.
COLOR BURST
Modulated Pedestal
The modulated pedestal test signal (also called
a three-level chrominance bar), shown in Figure
8.36, is composed of a 50 IRE luminance
pedestal, superimposed with three amplitudes
of modulated chrominance that has a phase
relative to the burst of –90° ±1°. The peak-topeak
amplitudes of the modulated chrominance
are 20 ±0.5, 40 ±0.5, and 80 ±0.5 IRE for
(M) NTSC and 20 ±0.5, 60 ±0.5, and 100 ±0.5
IREfor(B,D,G,H,I)PAL.Notea0IREsetup
is used. The rise and fall times of each modulation
packet envelope are 400 ±25 ns (NTSC
systems) or approximately 1 µs (PAL systems).
This test signal may be used to measure
chrominance-to-luminance intermodulation
and chrominance nonlinear gain.
MICROSECONDS = 14.9 20.2 51.5 56.7 61.8
80 IRE
BLANK LEVEL (0 IRE)
SYNC LEVEL
Figure 8.34. 80 IRE Modulated Ramp Test Signal for NTSC and PAL.

COLOR BURST
0
18
36
54
72
90
Video Test Signals 315
BLANK LEVEL (0 IRE)
SYNC LEVEL
Figure 8.35. Five-Step Modulated Staircase Test Signal for NTSC and PAL.
COLOR BURST
50 IRE
± 10 IRE
(± 10)
± 20 IRE
(± 30)
± 40 IRE
(± 50)
MICROSECONDS = 10.0 17.9 29.8 41.7 53.6 61.6
BLANK LEVEL (0 IRE)
SYNC LEVEL
Figure 8.36. Modulated Pedestal Test Signal for NTSC and PAL.
PAL IRE values are shown in parentheses.

316 Chapter 8: NTSC, PAL, and SECAM Overview
Multiburst
The multiburst test signal for (M) NTSC,
shown in Figure 8.37, consists of a white flag
with a peak amplitude of 100 ±1 IREandsix
frequency packets, each a specific frequency.
The packets have a 40 ±1 IREpedestalwith
peak-to-peak amplitudes of 60 ±0.5IRE.Notea
0 IRE setup is used and the starting and ending
point of each packet is at zero phase.
The ITU multiburst test signal for (B, D, G,
H, I) PAL, shown in Figure 8.38, consists of a 4
µs white flag with a peak amplitude of 80 ±1
IRE and six frequency packets, each a specific
frequency. The packets have a 50 ±1 IREpedestal
with peak-to-peak amplitudes of 60 ±0.5
IRE. Note the starting and ending points of
each packet are at zero phase. The gaps
between packets are 0.4–2.0 µs. The ITU multiburst
test signal may be present on line 18.
The multiburst signals are used to test the
frequency response of the system by measuring
the peak-to-peak amplitudes of the packets.
COLOR BURST
100 IRE
0.5
(4)
1.25
(8)
Line Bar
The line bar is a single 100 ±0.5 IRE (reference
white) pulse of 10 µs (PAL),18µs (NTSC),or
25 µs (PAL) that occurs anywhere within the
active scan line time (rise and fall times are ≤ 1
µs). Note the color burst is not present, and a 0
IRE setup is used. This test signal is used to
measure line time distortion (line tilt or H tilt).
A digital encoder or decoder does not generate
line time distortion; the distortion is generated
primarily by the analog filters and transmission
channel.
Multipulse
MHZ
(CYCLES)
2
(10)
3
(14)
3.58
(16)
4.2
(18)
Figure 8.37. Multiburst Test Signal for NTSC.
The (M) NTSC multipulse contains a 2T pulse
and 25T and 12.5T pulses with various high-frequency
components, as shown in Figure 8.39.
The (B, D, G, H, I) PAL multipulse is similar,
except 20T and 10T pulses are used, and there
is no 7.5 IRE setup. This test signal is typically
used to measure the frequency response of the
transmission channel.
70 IRE
40 IRE
10 IRE
BLANK LEVEL (0 IRE)
SYNC LEVEL

COLOR BURST
0.5 1 2 4 4.8 5.8
MICROSECONDS = 12 20 24 30 36 42 48 54 62
COLOR BURST
MHZ
Figure 8.38. ITU Multiburst Test Signal for PAL.
2T
1.0
25T
(20T)
2.0
12.5T
(10T)
3.0
(4.0)
12.5T
(10T)
3.58
(4.8)
12.5T
(10T)
4.2
(5.8)
12.5T
(10T)
MHZ
(MHZ)
Video Test Signals 317
80 IRE
50 IRE
20 IRE
BLANK LEVEL (0 IRE)
SYNC LEVEL
Figure 8.39. Multipulse Test Signal for NTSC and PAL. PAL values are shown in parentheses.

318 Chapter 8: NTSC, PAL, and SECAM Overview
Field Square Wave
The field square wave contains 100 ±0.5 IRE
pulses for the entire active line time for odd
fields and blanked scan lines for even fields.
Note the color burst is not present and a 0 IRE
setup is used. This test signal is used to measure
field time distortion (field tilt or V tilt). A
digital encoder or decoder does not generate
field time distortion; the distortion is generated
primarily by the analog filters and transmission
channel.
3.58 MHZ
COLOR BURST
(9 CYCLES)
+ 20
- 20
100 IRE
2T 12.5T
Composite Test Signal
MICROSECONDS = 12 30 34 37 42 46 49 52 55 58 61
NTC-7 Version for NTSC
The NTC (U. S. Network Transmission Committee)
has developed a composite test signal
that may be used to test several video parameters,
rather than using multiple test signals.
The NTC-7 composite test signal for NTSC
systems (shown in Figure 8.40) consists of a
100 IRE line bar, a 2T pulse, a 12.5T chrominance
pulse, and a 5-step modulated staircase
signal.
0
18
36
54
72
90
BLANK LEVEL (0 IRE)
SYNC LEVEL (– 40 IRE)
Figure 8.40. NTC-7 Composite Test Signal for NTSC, With Corresponding IRE Values.

The line bar has a peak amplitude of 100
±0.5 IRE, and 10–90% rise and fall times of 125
±5 nswithanintegratedsine-squaredshape.It
has a width at the 60 IRE level of 18 µs.
The 2T pulse has a peak amplitude of 100
±0.5 IRE, with a half-amplitude width of 250
±10 ns.
The 12.5T chrominance pulse has a peak
amplitude of 100 ±0.5 IRE, with a half-amplitude
width of 1562.5 ±50 ns.
The 5-step modulated staircase signal consists
of 5 luminance steps superimposed with a
40 ±0.5 IRE subcarrier that has a phase of 0°
±1° relative to the burst. The rise and fall times
of each modulation packet envelope are 400
±25 ns.
TheNTC-7compositetestsignalmaybe
present on line 17.
4.43 MHZ
COLOR BURST
(10 CYCLES)
2T
100 IRE 100
MICROSECONDS = 12 22 26 30 40 44 48 52 56 60
0
20
40
60
80
Video Test Signals 319
ITU Version for PAL
The ITU (BT.628 and BT.473) has developed a
composite test signal that may be used to test
several video parameters, rather than using
multiple test signals. The ITU composite test
signal for PAL systems (shown in Figure 8.41)
consists of a white flag, a 2T pulse, and a 5-step
modulated staircase signal.
The white flag has a peak amplitude of 100
±1 IREandawidthof10µs.
The 2T pulse has a peak amplitude of 100
±0.5 IRE, with a half-amplitude width of 200
±10 ns.
The 5-step modulated staircase signal consists
of 5 luminance steps (whose IRE values
are shown in Figure 8.41) superimposed with a
42.86 ±0.5 IRE subcarrier that has a phase of
60° ±1° relative to the U axis. The rise and fall
times of each modulation packet envelope are
approximately 1 µs.
BLANK LEVEL (0 IRE)
SYNC LEVEL (– 43 IRE)
Figure 8.41. ITU Composite Test Signal for PAL, With Corresponding IRE Values.

320 Chapter 8: NTSC, PAL, and SECAM Overview
The ITU composite test signal may be
present on line 330.
U.K. Version
The United Kingdom allows the use of a
slightly different test signal since the 10T
pulse is more sensitive to delay errors than the
20T pulse (at the expense of occupying less
chrominance bandwidth). Selection of an
appropriate pulse width is a trade-off between
occupying the PAL chrominance bandwidth as
fully as possible and obtaining a pulse with sufficient
sensitivity to delay errors. Thus, the
national test signal (developed by the British
Broadcasting Corporation and the Independent
Television Authority) in Figure 8.42 may
be present on lines 19 and 332 for (I) PAL systems
in the United Kingdom.
4.43 MHZ
COLOR BURST
(10 CYCLES)
2T 10T
100 IRE 100
MICROSECONDS = 12 22 26 30 34 40 44 48 52 56 60
The white flag has a peak amplitude of 100
±1 IREandawidthof10µs.
The 2T pulse has a peak amplitude of 100
±0.5 IRE, with a half-amplitude width of 200
±10 ns.
The 10T chrominance pulse has a peak
amplitude of 100 ±0.5 IRE.
The 5-step modulated staircase signal consists
of 5 luminance steps (whose IRE values
are shown in Figure 8.42) superimposed with a
21.43 ±0.5 IRE subcarrier that has a phase of
60° ±1° relative to the U axis. The rise and fall
times of each modulation packet envelope is
approximately 1 µs.
Figure 8.42. United Kingdom (I) PAL National Test Signal #1,
With Corresponding IRE Values.
0
20
40
60
80
BLANK LEVEL (0 IRE)
SYNC LEVEL (– 43 IRE)

Combination Test Signal
NTC-7 Version for NTSC
The NTC (U. S. Network Transmission Committee)
has also developed a combination test
signal that may be used to test several video
parameters, rather than using multiple test signals.
The NTC-7 combination test signal for
NTSC systems (shown in Figure 8.43) consists
of a white flag, a multiburst, and a modulated
pedestal signal.
The white flag has a peak amplitude of 100
±1IREandawidthof4µs.
The multiburst has a 50 ±1 IREpedestal
with peak-to-peak amplitudes of 50 ±0.5 IRE.
The starting point of each frequency packet is
at zero phase. The width of the 0.5 MHz packet
is 5 µs; the width of the remaining packets is 3
µs.
COLOR BURST
100 IRE
MHZ
0.5 1 2 3 3.58 4.2
MICROSECONDS = 12 18 24 28 32 36 40 46 50 54 60
Video Test Signals 321
The 3-step modulated pedestal is composed
of a 50 IRE luminance pedestal, superimposed
with three amplitudes of modulated
chrominance (20 ±0.5, 40 ±0.5, and 80 ±0.5 IRE
peak-to-peak) that have a phase of –90° ±1° relative
to the burst. The rise and fall times of
each modulation packet envelope are 400 ±25
ns.
The NTC-7 combination test signal may be
present on line 280.
ITU Version for PAL
The ITU (BT.473) has developed a combination
test signal that may be used to test several
video parameters, rather than using multiple
test signals. The ITU combination test signal
for PAL systems (shown in Figure 8.44) consists
of a white flag, a 2T pulse, a 20T modulated
chrominance pulse, and a 5-step
luminance staircase signal.
Figure 8.43. NTC-7 Combination Test Signal for NTSC.
50 IRE
BLANK LEVEL (0 IRE)
SYNC LEVEL

322 Chapter 8: NTSC, PAL, and SECAM Overview
The line bar has a peak amplitude of 100 ±1
IRE and a width of 10 µs.
The 2T pulse has a peak amplitude of 100
±0.5 IRE, with a half-amplitude width of 200
±10 ns.
The 20T chrominance pulse has a peak
amplitude of 100 ±0.5 IRE, with a half-amplitude
width of 2.0 ±0.06 µs.
The 5-step luminance staircase signal consists
of 5 luminance steps, at 20, 40, 60, 80 and
100 ±0.5 IRE.
The ITU combination test signal may be
present on line 17.
ITU ITS Version for PAL
The ITU (BT.473) has developed a combination
ITS (insertion test signal) that may be
used to test several PAL video parameters,
rather than using multiple test signals. The
ITU combination ITS for PAL systems (shown
in Figure 8.45) consists of a 3-step modulated
pedestal with peak-to-peak amplitudes of 20,
4.43 MHZ
COLOR BURST
(10 CYCLES)
2T 20T
100 IRE 100 IRE
MICROSECONDS = 12 22 26 32 40 44 48 52 56 62
Figure 8.44. ITU Combination Test Signal for PAL.
60, and 100 ±1 IRE, and an extended subcarrier
packet with a peak-to-peak amplitude of 60
±1 IRE. The rise and fall times of each subcarrier
packet envelope are approximately 1 µs.
The phase of each subcarrier packet is 60°
±1° relative to the U axis. The tolerance on the
50 IRE level is ±1IRE.
TheITUcompositeITSmaybepresenton
line 331.
U. K. Version
The United Kingdom allows the use of a
slightly different test signal, as shown in Figure
8.46. It may be present on lines 20 and 333
for (I) PAL systems in the United Kingdom.
The test signal consists of a 50 IRE luminance
bar, part of which has a 100 IRE subcarrier
superimposed that has a phase of 60°
±1° relative to the U axis, and an extended
burst of subcarrier on the second half of the
scan line.
20
40
60
80
BLANK LEVEL (0 IRE)
SYNC LEVEL (– 43 IRE)

4.43 MHZ
COLOR BURST
(10 CYCLES)
60
40
80
20
100
IRE
MICROSECONDS = 12 14 18 22 28 34 60
Figure 8.45. ITU Combination ITS Test Signal for PAL.
4.43 MHZ
COLOR BURST
(10 CYCLES)
100 IRE
50 IRE
MICROSECONDS = 12 14 28 32 34 62
Video Test Signals 323
80 IRE
50 IRE
20 IRE
BLANK LEVEL (0 IRE)
SYNC LEVEL (– 43 IRE)
21.43 IRE
BLANK LEVEL (0 IRE)
–21.43 IRE
Figure 8.46. United Kingdom (I) PAL National Test Signal #2.
SYNC LEVEL (– 43 IRE)

324 Chapter 8: NTSC, PAL, and SECAM Overview
T Pulse
Square waves with fast rise times cannot be
used for testing video systems, since attenuation
and phase shift of out-of-band components
cause ringing in the output signal, obscuring
the in-band distortions being measured. T, or
sin 2 , pulses are bandwidth-limited, so are used
for testing video systems.
The 2T pulse is shown in Figure 8.47 and,
like the T pulse, is obtained mathematically by
squaring a half-cycle of a sine wave. T pulses
are specified in terms of half amplitude duration
(HAD), which is the pulse width measured
at 50% of the pulse amplitude. Pulses with
HADs that are multiples of the time interval T
–250 0 250
(A)
A
50%
1.0
0.8
0.6
0.4
0.2
250 NS
TIME (NS)
0 1 2 3 4 5
(C)
are used to test video systems. As seen in Figures
8.39 through 8.44, T, 2T, 12.5T and 25T
pulses are common when testing NTSC video
systems, whereas T, 2T, 10T, and 20T pulses
are common for PAL video systems.
T is the Nyquist interval or
1/2FC where FC is the cutoff frequency of the video
system.ForNTSC,FCis 4 MHz, whereas FC for PAL systems is 5 MHz. Therefore, T for
NTSC systems is 125 ns and for PAL systems it
is 100 ns. For a T pulse with a HAD of 125 ns, a
2T pulse has a HAD of 250 ns, and so on. The
frequency spectra for the 2T pulse is shown in
240 NS
10%
2A
–250 0 250
(B)
A
FREQUENCY (MHZ)
90%
TIME (NS)
Figure 8.47. The T Pulse. (a) 2T pulse. (b) 2T step. (c) Frequency spectra of the 2T pulse.

Figure 8.47 and is representative of the energy
content in a typical character generator waveform.
To generate smooth rising and falling
edges of most video signals, a T step (generated
by integrating a T pulse) is typically used.
Tstepshave10–90% rise/fall times of 0.964T
and a well-defined bandwidth. The 2T step generated
from a 2T pulse is shown in Figure 8.47.
The 12.5T chrominance pulse, illustrated
in Figure 8.48, is a good test signal to measure
any chrominance-to-luminance timing error
since its energy spectral distribution is
bunched in two relatively narrow bands. Using
this signal detects differences in the luminance
and chrominance phase distortion, but not
between other frequency groups.
0.5
–1562.5 0 1562.5
(A)
50%
0.5
–0.5
(B)
1562.5 NS
TIME (NS)
TIME (NS)
VBI Data
50%
1.0
–1562.5 0 1562.5
(C)
1562.5 NS
TIME (NS)
VBI Data 325
VBI (vertical blanking interval) data may be
inserted up to about 5 scan lines into the active
picture region to ensure it won't be deleted by
equipment replacing the VBI, by DSS MPEG
which deletes the VBI, or by cable systems
inserting their own VBI data. This is common
practice by Neilson and others to ensure their
programming and commercial tracking data
gets through the distribution systems to the
receivers. In most cases, this will be unseen
since it is masked by the TV’s overscan.
Timecode
Two types of time coding are commonly used,
as defined by ANSI/SMPTE 12M and IEC 461:
Figure 8.48. The 12.5T Chrominance Pulse. (a) Luma component.
(b) Chroma component. (c) Addition of (a) and (b).

326 Chapter 8: NTSC, PAL, and SECAM Overview
longitudinal timecode (LTC) and vertical interval
timecode (VITC).
The LTC is recorded on a separate audio
track; as a result, the analog VCR must use
high-bandwidth amplifiers and audio heads.
This is due to the time code frequency increasing
as tape speed increases, until the point that
the frequency response of the system results
in a distorted time code signal that may not be
read reliably. At slower tape speeds, the time
code frequency decreases, until at very low
tape speeds or still pictures, the time code
information is no longer recoverable.
TheVITCisrecordedaspartofthevideo
signal; as a result, the time code information is
always available, regardless of the tape speed.
However,theLTCallowsthetimecodesignal
to be written without writing a video signal; the
VITC requires the video signal to be changed if
a change in time code information is required.
The LTC therefore is useful for synchronizing
multiple audio or audio/video sources.
Frame Dropping
If the field rate is 60/1.001 fields per second,
straight counting at 60 fields per second yields
an error of about 108 frames for each hour of
running time. This may be handled in one of
three ways:
Nondrop frame: During a continuous
recording, each time count increases
by 1 frame. In this mode, the drop
frameflagwillbea“0.”
Drop frame: To minimize the timing
error, the first two frame numbers (00
and 01) at the start of each minute,
except for minutes 00, 10, 20, 30, 40,
and 50, are omitted from the count. In
this mode, the drop frame flag will be a
“1.”
Drop frame for (M) PAL: To minimize
the timing error, the first four frame
numbers (00 to 03) at the start of
every second minute (even minute
numbers) are omitted from the count,
except for minutes 00, 20, and 40. In
this mode, the drop frame flag will be a
“1.”
Even with drop framing, there is a longterm
error of about 2.26 frames per 24 hours.
This error accumulation is the reason timecode
generators must be periodically reset if
they are to maintain any correlation to the correct
time-of-day. Typically, this “reset-to-realtime”
is referred to as a “jam sync” procedure.
Some jam sync implementations reset the
timecode to 00:00:00.00 and, therefore, must
occur at midnight; others allow a true re-sync
to the correct time-of-day.
One inherent problem with jam sync correction
is the interruption of the timecode.
Although this discontinuity may be brief, it
may cause timecode readers to “hiccup” due to
the interruption.
Longitudinal Timecode (LTC)
The LTC information is transferred using a
separate serial interface, using the same electrical
interface as the AES/EBU digital audio
interfacestandard,andisrecordedonaseparate
track. The basic structure of the time data
is based on the BCD system. Tables 8.20 and
8.21 list the LTC bit assignments and arrangement.
Note the 24-hour clock system is used.
LTC Timing
The modulation technique is such that a transition
occurs at the beginning of every bit
period. “1” is represented by a second transition
one-half a bit period from the start of the
bit. “0” is represented when there is no transition
within the bit period (see Figure 8.49).

VBI Data 327
Bit(s) Function Note Bit(s) Function Note
0–3 units of frames 58 flag 5 note 5
4–7 user group 1 59 flag 6 note 6
8–9 tens of frames 60–63 user group 8
10 flag 1 note 1 64 sync bit fixed”0”
11 flag 2 note 2 65 sync bit fixed”0”
12–15 user group 2 66 sync bit fixed”1”
16–19 units of seconds 67 sync bit fixed”1”
20–23 user group 3 68 sync bit fixed”1”
24–26 tens of seconds 69 sync bit fixed”1”
27 flag 3 note 3 70 sync bit fixed”1”
28–31 user group 4 71 sync bit fixed”1”
32–35 units of minutes 72 sync bit fixed”1”
36–39 user group 5 73 sync bit fixed”1”
40–42 tens of minutes 74 sync bit fixed”1”
43 flag 4 note 4 75 sync bit fixed”1”
44–47 user group 6 76 sync bit fixed”1”
48–51 units of hours 77 sync bit fixed”1”
52–55 user group 7 78 sync bit fixed”0”
56–57 tens of hours 79 sync bit fixed”1”
Notes
1. Drop frame flag. 525/60 and 1125/60 systems: “1” if frame numbers are being dropped, “0” if no frame dropping
is done. 625/50 systems: “0”.
2. Color frame flag. 525/60 systems: “1” if even units of frame numbers identify fields 1 and 2 and odd units of field
numbers identify fields 3 and 4. 625/50 systems: “1” if timecode is locked to the video signal in accordance
with 8-field sequence and the video signal has the “preferred subcarrier-to-line-sync phase”. 1125/60 systems:
“0”.
3. 525/60 and 1125/60 systems: Phase correction. This bit shall be put in a state so that every 80-bit word contains
an even number of “0”s. 625/50 systems: Binary group flag 0.
4. 525/60 and 1125/60 systems: Binary group flag 0. 625/50 systems: Binary group flag 2.
5. Binary group flag 1.
6. 525/60 and 1125/60 systems: Binary group flag 2. 625/50 systems: Phase correction. This bit shall be put in a
state so that every 80-bit word contains an even number of “0”s.
Table 8.20. LTC Bit Assignments.

328 Chapter 8: NTSC, PAL, and SECAM Overview
Frames (count 0–29 for 525/60 systems, 0–24 for 625/50 systems)
units of frames (bits 0–3) 4-bit BCD (count 0–9); bit 0 is LSB
tens of frames (bits 8–9) 2-bit BCD (count 0–2); bit 8 is LSB
units of seconds (bits 16–19)
Seconds
4-bit BCD (count 0–9); bit 16 is LSB
tens of seconds (bits 24–26) 3-bit BCD (count 0–5); bit 24 is LSB
units of minutes (bits 32–35)
Minutes
4-bit BCD (count 0–9); bit 32 is LSB
tens of minutes (bits 40–42) 3-bit BCD (count 0–5); bit 40 is LSB
units of hours (bits 48–51)
Hours
4-bit BCD (count 0–9); bit 48 is LSB
tens of hours (bits 56–57) 2-bit BCD (count 0–2); bit 56 is LSB
Table 8.21. LTC Bit Arrangement.
"0" "1"
Figure 8.49. LTC Data Bit Transition Format.

The signal has a peak-to-peak amplitude of 0.5–
4.5V, with rise and fall times of 40 ±10 µs (10%
to 90% amplitude points).
Becausetheentireframetimeisusedto
generate the 80-bit LTC information, the bit
rate (in bits per second) may be determined
by:
FC =80FV where FV istheverticalframerateinframes
persecond.The80bitsoftimecodeinformation
are output serially, with bit 0 being first.
The LTC word occupies the entire frame time,
and the data must be evenly spaced throughout
this time. The start of the LTC word occurs
at the beginning of line 5 ±1.5 lines for 525/60
systems, at the beginning of line 2 ±1.5 lines
for 625/50 systems, and at the vertical sync
timing reference of the frame ±1 line for 1125/
60 systems.
Vertical Inter val Time Code (VITC)
The VITC is recorded during the vertical
blanking interval of the video signal in both
fields. Since it is recorded with the video, it can
be read in still mode. However, it cannot be rerecorded
(or restriped). Restriping requires
dubbing down a generation, deleting and
inserting a new time code. For YPbPr and Svideo
interfaces, VITC is present on the Y signal.
For analog RGB interfaces, VITC is
present on all three signals.
As with the LTC, the basic structure of the
time data is based on the BCD system. Tables
8.22 and 8.23 list the VITC bit assignments and
arrangement. Note the 24-hour clock system is
used.
VITC Cyclic Redundancy Check
Eight bits (82–89) are reserved for the code
word for error detection by means of cyclic
redundancy checking. The generating polyno-
VBI Data 329
mial, x 8 + 1, applies to all bits from 0 to 81,
inclusive. Figure 8.50 illustrates implementing
the polynomial using a shift register. During
passage of timecode data, the multiplexer is in
position 0 and the data is output while the CRC
calculation is done simultaneously by the shift
register. After all the timecode data has been
output, the shift register contains the CRC
value, and switching the multiplexer to position
1 enables the CRC value to be output.
When the process is repeated on decoding, the
shift register should contain all zeros if no
errors exist.
VITC Timing
The modulation technique is such that each
state corresponds to a binary state, and a transition
occurs only when there is a change in
the data between adjacent bits from a “1” to “0”
or “0” to “1”. No transitions occur when adjacent
bits contain the same data. This is commonly
referred to as “non-return to zero”
(NRZ). Synchronization bit pairs are inserted
throughout the VITC data to assist the receiver
in maintaining the correct frequency lock.
The bit rate (F C )isdefinedtobe:
F C = 115 F H ± 2%
where F H is the horizontal line frequency. The
90 bits of time code information are output
serially, with bit 0 being first. For 625/50 systems,
lines 19 and 332 are commonly used for
the VITC. For 525/60 systems, lines 14 and
277 are commonly used. To protect the VITC
against drop-outs, it may also be present two
scan lines later, although any two nonconsecutive
scan lines per field may be used.
Figure 8.51 illustrates the timing of the
VITC data on the scan line. The data must be
evenly spaced throughout the VITC word. The
10% to 90% rise and fall times of the VITC bit
data should be 200 ±50 ns (525/60 and 625/50

330 Chapter 8: NTSC, PAL, and SECAM Overview
Bit(s) Function Note Bit(s) Function Note
0 sync bit fixed “1” 42–45 units of minutes
1 sync bit fixed “0” 46–49 user group 5
2–5 units of frames 50 sync bit fixed “1”
6–9 usergroup1 51 syncbit fixed“0”
10 sync bit fixed “1” 52–54 tens of minutes
11 sync bit fixed “0” 55 flag 4 note 4
12–13 tens of frames 56–59 user group 6
14 flag 1 note 1 60 sync bit fixed “1”
15 flag 2 note 2 61 sync bit fixed”0”
16–19 user group 2 62–65 units of hours
20 sync bit fixed “1” 66–69 user group 7
21 sync bit fixed “0” 70 sync bit fixed”1”
22–25 units of seconds 71 sync bit fixed”0”
26–29 user group 3 72–73 tens of hours
30 sync bit fixed “1” 74 flag 5 note 5
31 sync bit fixed “0” 75 flag 6 note 6
32–34 tens of seconds 76–79 user group 8
35 flag 3 note 3 80 sync bit fixed”1”
36–39 user group 4 81 sync bit fixed”0”
40 sync bit fixed “1” 82–89 CRC group
41 sync bit fixed “0”
Notes
1. Drop frame flag. 525/60 and 1125/60 systems: “1” if frame numbers are being dropped, “0” if no frame
dropping is done. 625/50 systems: “0”.
2. Color frame flag. 525/60 systems: “1” if even units of frame numbers identify fields 1 and 2 and odd units
of field numbers identify fields 3 and 4. 625/50 systems: “1” if timecode is locked to the video signal in
accordance with 8-field sequence and the video signal has the “preferred subcarrier-to-line-sync
phase”. 1125/60 systems: “0”.
3. 525/60 systems: Field flag. “0” during fields 1 and 3, “1” during fields 2 and 4. 625/50 systems: Binary
group flag 0. 1125/60 systems: Field flag. “0” during field 1, “1” during field 2.
4. 525/60 and 1125/60 systems: Binary group flag 0. 625/50 systems: Binary group flag 2.
5. Binary group flag 1.
6. 525/60 and 1125/60 systems: Binary group flag 2. 625/50 systems: Field flag. “0” during fields 1, 3, 5, and
7, “1” during fields 2, 4, 6, and 8.
Table 8.22. VITC Bit Assignments.

Frames (count 0–29 for 525/60 systems, 0–24 for 625/50 systems)
units of frames (bits 2–5) 4-bit BCD (count 0–9); bit 2 is LSB
tens of frames (bits 12–13) 2-bit BCD (count 0–2); bit 12 is LSB
units of seconds (bits 22–25)
Seconds
4-bit BCD (count 0–9); bit 22 is LSB
tens of seconds (bits 32–34) 3-bit BCD (count 0–5); bit 32 is LSB
units of minutes (bits 42–45)
Minutes
4-bit BCD (count 0–9); bit 42 is LSB
tens of minutes (bits 52–54) 3-bit BCD (count 0–5); bit 52 is LSB
units of hours (bits 62–65)
Hours
4-bit BCD (count 0–9); bit 62 is LSB
tens of hours (bits 72–73) 2-bit BCD (count 0–2); bit 72 is LSB
DATA
IN
XOR
Table 8.23. VITC Bit Arrangement.
D Q D Q D Q D Q D Q D Q D Q D Q
Figure 8.50. VITC CRC Generation.
0
1
MUX
VBI Data 331
DATA
+
CRC
OUT

332 Chapter 8: NTSC, PAL, and SECAM Overview
10 µS MIN
(19 BITS)
80 ±10
IRE
63.556 µS (115 BITS)
50.286 µS (90 BITS)
525 / 60 SYSTEMS
2.1 µS MIN
HSYNC HSYNC
11.2 µS MIN
(21 BITS)
78 ±7
IRE
64 µS (115 BITS)
49.655 µS (90 BITS)
625 / 50 SYSTEMS
1.9 µS MIN
HSYNC HSYNC
2.7 µS MIN
(10.5 BITS)
78 ±7
IRE
29.63 µS (115 BITS)
23.18 µS (90 BITS)
1125 / 60 SYSTEMS
1.5 µS
MIN
HSYNC HSYNC
Figure 8.51. VITC Position and Timing.

User Bits Content
Timecode Referenced
to External Clock
BGF2 BGF1 BGF0
user defined no 0 0 0
8-bit character set1 no 0 0 1
user defined yes 0 1 0
reser ved unassigned 0 1 1
date and time zone3 no 1 0 0
page / line2 no 1 0 1
date and time zone3 yes 1 1 0
page / line2 yes 1 1 1
1 Conforming to ISO/IEC 646 or 2022.
2 Described in SMPTE 262M.
3 Described in SMPTE 309M. See Tables 8.25 through 8.27.
Table 8.24. LTC and VITC Binary Group Flag (BGF) Bit Definitions.
USER
GROUPS
7–BIT ISO:
8–BIT ISO:
1
3
5
7
B1 B2 B3 B4
A1 A2 A3 A4
2
4
6
8
ONE ISO CHARACTER
B5 B6 B7 0
A5 A6 A7 A8
Figure 8.52. Use of Binary Groups to Describe
ISO Characters Coded With 7 or 8 Bits.
VBI Data 333

334 Chapter 8: NTSC, PAL, and SECAM Overview
MJD flag: “0” = YYMMDD format, “1” =MJDformat.
systems) or 100 ±25 ns (1125/60 systems)
before adding it to the video signal to avoid
possible distortion of the VITC signal by downstream
chrominance circuits. In most circumstances,
the analog lowpass filters after the
video D/A converters should suffice for the filtering.
User Bits
The binary group flag (BGF) bits shown in
Table 8.24 specify the content of the 32 user
bits. The 32 user bits are organized as eight
groups of four bits each.
User Group 8 User Group 7
Bit 3 Bit 2 Bit 1 Bit 0 Bit 3 Bit 2 Bit 1 Bit 0
MJD Flag 0 time zone offset code 00 H –3F H
Table 8.25. Date and Time Zone Format Coding.
User
Group
Assignment Value Description
1 D 0–9 day units
2 D 0–3 day units
3 M 0–9 month units
4 M 0, 1 month units
5 Y 0–9 yearunits
6 Y 0–9 yearunits
Table 8.26. YYMMDD Date Format.
The user bits are intended for storage of
data by users. The 32 bits may be assigned in
any manner without restriction, if indicated as
user-defined by the binary group flags.
If an 8-bit character set conforming to
ISO/IEC 646 or 2022 is indicated by the binary
group flags, the characters are to be inserted
asshowninFigure8.52.Notethatsomeuser
bits will be decoded before the binary group
flags are decoded; therefore, the decoder must
store the early user data before any processing
is done.

Code Hours Code Hours Code Hours
00 UTC 16 UTC + 10.00 2C UTC + 09.30
01 UTC – 01.00 17 UTC + 09.00 2D UTC + 08.30
02 UTC – 02.00 18 UTC + 08.00 2E UTC + 07.30
03 UTC – 03.00 19 UTC + 07.00 2F UTC + 06.30
04 UTC – 04.00 1A UTC – 06.30 30 TP–1
05 UTC – 05.00 1B UTC – 07.30 31 TP–0
06 UTC – 06.00 1C UTC – 08.30 32 UTC + 12.45
07 UTC – 07.00 1D UTC – 09.30 33 reserved
08 UTC – 08.00 1E UTC – 10.30 34 reserved
09 UTC – 09.00 1F UTC – 11.30 35 reserved
0A UTC – 00.30 20 UTC + 06.00 36 reserved
0B UTC – 01.30 21 UTC + 05.00 37 reserved
0C UTC – 02.30 22 UTC + 04.00 38 user defined
0D UTC – 03.30 23 UTC + 03.00 39 unknown
0E UTC – 04.30 24 UTC + 02.00 3A UTC + 05.30
0F UTC – 05.30 25 UTC + 01.00 3B UTC + 04.30
10 UTC – 10.00 26 reserved 3C UTC + 03.30
11 UTC – 11.00 27 reserved 3D UTC + 02.30
12 UTC – 12.00 28 TP–3 3E UTC + 01.30
13 UTC + 13.00 29 TP–2 3F UTC + 00.30
14 UTC + 12.00 2A UTC + 11.30
15 UTC + 11.00 2B UTC + 10.30
Table 8.27. Time Zone Offset Codes.
VBI Data 335

336 Chapter 8: NTSC, PAL, and SECAM Overview
When the user groups are used to transfer
time zone and date information, user groups 7
and8specifythetimezoneandtheformatof
thedateintheremainingsixusergroups,as
showninTables8.25and8.27.Thedatemay
be either a six-digit YYMMDD format (Table
8.26) or a six-digit modified Julian date (MJD),
as indicated by the MJD flag.
Closed Captioning
This section reviews closed captioning for the
hearing impaired in the United States. Closed
captioningandtextaretransmittedduringthe
blanked active line-time portion of lines 21 and
284.
Extended data services (XDS) also may be
transmitted during the blanked active line-time
BLANK LEVEL
SYNC LEVEL
50 ±2 IRE
40 IRE
10.5 ± 0.25 µS
3.58 MHZ
COLOR BURST
(9 CYCLES)
10.003 ± 0.25 µS
12.91 µS
7 CYCLES
OF 0.5035 MHZ
(CLOCK RUN–IN)
portion of line 284. XDS may indicate the program
name, time into the show, time remainingtotheend,andsoon.
Note that due to editing before transmission,
it may be possible that the caption information
is moved down a scan line or two.
Therefore, caption decoders should monitor
more than just lines 21 and 284 for caption
information.
Waveform
The data format for both lines consists of a
clockrun-insignal,astartbit,andtwo7-bit
plus parity words of ASCII data (per X3.4-
1967). For YPbPr and S-video interfaces, captioning
is present on the Y signal. For analog
RGB interfaces, captioning is present on all
three signals.
TWO 7–BIT + PARITY
ASCII CHARACTERS
(DATA)
27.382 µS 33.764 µS
S
T
A
R
T
D0–D6 P D0–D6
A
R
I
T
Y
Figure 8.53. NTSC Line 21 and Line 284 Closed Captioning Timing.
P
A
R
I
T
Y
240–288 NS
RISE / FALL
TIMES
(2T BAR
SHAPING)

Figure 8.53 illustrates the waveform and
timing for transmitting the closed captioning
andXDSinformationandconformstotheTelevision
Synchronizing Waveform for Color
Transmission in Subpart E, Part 73 of the FCC
Rules and Regulations and EIA-608. The clock
run-in is a 7-cycle sinusoidal burst that is frequency-locked
and phase-locked to the caption
data and is used to provide synchronization for
the decoder. The nominal data rate is 32× F H .
However, decoders should not rely on this timing
relationship due to possible horizontal timing
variations introduced by video processing
circuitry and VCRs. After the clock run-in signal,
the blanking level is maintained for a two
data bit duration, followed by a “1” start bit.
The start bit is followed by 16 bits of data, composed
of two 7-bit + odd parity ASCII characters.
Caption data is transmitted using a non–
return-to-zero (NRZ) code; a “1” corresponds
to the 50 ± 2IRElevelanda“0” corresponds to
the blanking level (0–2 IRE). The negativegoing
crossings of the clock are coherent with
the data bit transitions.
Typical decoders specify the time between
the 50% points of sync and clock run-in to be
10.5 ±0.5 µs, with a ±3% tolerance on F H ,50±12
IRE for a “1” bit, and –2 to+12IREfora“0” bit.
Decoders must also handle bit rise/fall times
of 240–480 ns.
NUL characters (00 H ) should be sent
when no display or control characters are
being transmitted. This, in combination with
the clock run-in, enables the decoder to determine
whether captioning or text transmission
is being implemented.
If using only line 21, the clock run-in and
data do not need to be present on line 284.
However, if using only line 284, the clock runin
and data should be present on both lines 21
and 284; data for line 21 would consist of NUL
characters.
VBI Data 337
At the decoder, as shown in Figure 8.54,
the display area of a 525-line 4:3 interlaced display
is typically 15 rows high and 34 columns
wide. The vertical display area begins on lines
43 and 306 and ends on lines 237 and 500. The
horizontal display area begins 13 µs andends
58 µs, after the leading edge of horizontal sync.
In text mode, all rows are used to display
text; each row contains a maximum of 32 characters,
with at least a one-column wide space
on the left and right of the text. The only transparent
area is around the outside of the text
area.
In caption mode, text usually appears only
on rows 1–4 or12–15; the remaining rows are
usually transparent. Each row contains a maximum
of 32 characters, with at least a one-column
wide space on the left and right of the
text.
Some caption decoders support up to 48
columns per row, and up to 16 rows, allowing
some customization for the display of caption
data.
Basic Ser vices
There are two types of display formats: text
and captioning. In understanding the operation
of the decoder, it is easier to visualize an invisible
cursor that marks the position where the
next character will be displayed. Note that if
you are designing a decoder, you should obtain
the latest FCC Rules and Regulations and EIA-
608 to ensure correct operation, as this section
is only a summary.
Text Mode
Text mode uses 7–15 rows of the display and is
enabled upon receipt of the Resume Text Display
or Text Restart code. When text mode has
been selected, and the text memory is empty,
the cursor starts at the top-most row, character
1 position. Once all the rows of text are displayed,
scrolling is enabled.

338 Chapter 8: NTSC, PAL, and SECAM Overview
With each carriage return received, the
top-most row of text is erased, the text is rolled
up one row (over a maximum time of 0.433 seconds),
the bottom row is erased, and the cursor
is moved to the bottom row, character 1
position. If new text is received while scrolling,
it is seen scrolling up from the bottom of the
display area. If a carriage return is received
while scrolling, the rows are immediately
moved up one row to their final position.
Once the cursor moves to the character 32
position on any row, any text received before a
carriage return, preamble address code, or
backspace will be displayed at the character 32
position, replacing any previous character at
that position. The Text Restart command
erases all characters on the display and moves
the cursor to the top row, character 1 position.
LINE COUNT
LINE 43
56
69
82
95
108
121
134
147
160
173
186
199
212
225
237
45.02 µS (34 CHARACTERS)
ROW 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Figure 8.54. Closed Captioning Display Format.
Captioning Mode
Captioning has several modes available, including
roll-up, pop-on, and paint-on.
Roll-up captioning is enabled by receiving
one of the miscellaneous control codes to
select the number of rows displayed. “Roll-up
captions, 2 rows” enables rows 14 and 15; “rollup
captions, 3 rows” enables rows 13–15, “rollup
captions, 4 rows” enables rows 12–15.
Regardless of the number of rows enabled, the
cursor remains on row 15. Once row 15 is full,
the rows are scrolled up one row (at the rate of
one dot per frame), and the cursor is moved
back to row 15, character 1.
Pop-on captioning may use rows 1–4or12–
15, and is initiated by the Resume Caption
Loading command. The display memory is
essentially double-buffered. While memory
buffer 1 is displayed, memory buffer 2 is being
loaded with caption data. At the receipt of a
CAPTIONS
OR
INFOTEXT
INFOTEXT
ONLY
CAPTIONS
OR
INFOTEXT

End of Caption code, memory buffer 2 is displayed
while memory buffer 1 is being loaded
with new caption data.
Paint-on captioning, enabled by the
Resume Direct Captioning command, is similar
to Pop-on captioning, but no double-buffering
is used; caption data is loaded directly into
display memory.
Three types of control codes (preamble
address codes, midrow codes, and miscellaneous
control codes) are used to specify the
format, location, and attributes of the characters.
Each control code consists of two bytes,
transmitted together on line 21 or line 284. On
line 21, they are normally transmitted twice in
succession to help ensure correct reception.
They are not transmitted twice on line 284 to
minimize bandwidth used for captioning.
The first byte is a nondisplay control byte
with a range of 10 H to 1F H ; the second byte is a
display control byte in the range of 20 H to 7F H .
At the beginning of each row, a control code is
sent to initialize the row. Caption roll-up and
text modes allow either a preamble address
START
BIT
PREAMBLE CONTROL CODE
(TRANSMITTED TWICE)
NON-DISPLAY
CONTROL
CHARACTER
(7 BITS
LSB FIRST)
ODD
PARITY
BIT
DISPLAY
CONTROL
CHARACTER
(7 BITS
LSB FIRST)
IDENTIFICATION CODE, ROW POSITION, INDENT,
AND DISPLAY CONDITION INSTRUCTIONS
ODD
PARITY
BIT
START
BIT
CAPTION TEXT UP TO 32
CHARACTERS PER ROW
FIRST
TEXT
CHARACTER
(7 BITS
LSB FIRST)
ODD
PARITY
BIT
SECOND
TEXT
CHARACTER
(7 BITS
LSB FIRST)
BEGINNING OF DISPLAYED
CAPTION
VBI Data 339
code or midrow control code at the start of a
row; the other caption modes use a preamble
address code to initialize a row. The preamble
address codes are illustrated in Figure 8.55
and Table 8.28.
The midrow codes are typically used
within a row to change the color, italics, underline,
and flashing attributes and should occur
only between words. Color, italics, and underline
are controlled by the preamble address
and midrow codes; flash on is controlled by a
miscellaneous control code. An attribute
remains in effect until another control code is
received or the end of row is reached. Each
row starts with a control code to set the color
and underline attributes (white nonunderlined
is the default if no control code is received
before the first character on an empty row).
The color attribute can be changed only by the
midrow code of another color; the italics
attribute does not change the color attribute.
However, a color attribute turns off the italics
attribute. The flash on command does not alter
the status of the color, italics, or underline
Figure 8.55. Closed Captioning Preamble Address Code Format.
ODD
PARITY
BIT

340 Chapter 8: NTSC, PAL, and SECAM Overview
Non-display Control Byte Display Control Byte
D6 D5 D4 D3 D2 D1 D0 D6 D5 D4 D3 D2 D1 D0
0 0 1 CH
0 0 1
0 1 0
1 0 1
1 1 0
U: “0” = no underline, “1” = underline
CH: “0” = data channel 1, “1” = data channel 2
Row Position
1 0
1
1 1 2
1 0 3
1 1 4
1 0 5
1 1 6
1 0 7
1 1 A B C D U
8
1 1 1
1
1
0
1
9
10
0 0 0 1 0 11
0 1 1
1 0 0
1 0 12
1 1 13
1 0 14
1 1 15
A B C D Attribute
0 0 0 0 white
0 0 0 1 green
0 0 1 0 blue
0 0 1 1 cyan
0 1 0 0 red
0 1 0 1 yellow
0 1 1 0 magenta
0 1 1 1 italics
1 0 0 0 indent0,white
1 0 0 1 indent4,white
1 0 1 0 indent8,white
1 0 1 1 indent 12, white
1 1 0 0 indent 16, white
1 1 0 1 indent 20, white
1 1 1 0 indent 24, white
1 1 1 1 indent 28, white
Table 8.28. Closed Captioning Preamble Address Codes. In text mode, the indent codes
may be used to perform indentation; in this instance, the row information is ignored.

attributes. However, a color or italics midrow
control code turns off the flash. Note that the
underline color is the same color as the character
being underlined; the underline resides on
dot row 11 and covers the entire width of the
character column.
Table 8.29, Figure 8.56, and Table 8.30
illustrate the midrow and miscellaneous control
code operation. For example, if it were the
end of a caption, the control code could be End
ofCaption(transmittedtwice).Itcouldbefollowed
by a preamble address code (transmitted
twice) to start another line of captioning.
Characters are displayed using a dot
matrix format. Each character cell is typically
16 samples wide and 26 samples high (16×26),
as shown in Figure 8.57. Dot rows 2–19 are
usually used for actual character outlines. Dot
rows 0, 1, 20, 21, 24, and 25 are usually blanked
to provide vertical spacing between characters,
and underlining is typically done on dot rows
VBI Data 341
22 and 23. Dot columns 0, 1, 14 and 15 are
blanked to provide horizontal spacing between
characters, except on dot rows 22 and 23 when
the underline is displayed. This results in
12×18 characters stored in character ROM.
Table 8.31 shows the basic character set.
Some caption decoders support multiple
character sizes within the 16×26 region, including
13×16, 13×24, 12×20, and 12×26. Not all
combinations generate a sensible result due to
the limited display area available.
Optional Captioning Features
Three sets of optional features are available for
advanced captioning decoders.
Optional Attributes
Additional color choices are available for
advanced captioning decoders, as shown in
Table 8.32.
Non-display Control Byte Display Control Byte
D6 D5 D4 D3 D2 D1 D0 D6 D5 D4 D3 D2 D1 D0 Attribute
0 0 1 CH 0 0 1 0 1 0
0 0 0
white
0 0 1 green
0 1 0 blue
0
1
1
0
1
0
U
cyan
red
1 0 1 yellow
1 1 0 magenta
1 1 1 italics
U: “0” = no underline, “1” = underline CH: “0” = data channel 1, “1” = data channel 2
Note: Italics is implemented as a two-dot slant to the right over the vertical range of the character. Some decoders
implement a one dot slant for every four scan lines. Underline resides on dot rows 22 and 23, and covers the
entire column width.
Table 8.29. Closed Captioning Midrow Codes.

342 Chapter 8: NTSC, PAL, and SECAM Overview
START
BIT
TEXT
CHARACTER
(7 BITS
LSB FIRST)
TEXT MID–ROW CONTROL CODE
(TRANSMITTED TWICE)
ODD
PARITY
BIT
TEXT
CHARACTER
(7 BITS
LSB FIRST)
ODD
PARITY
BIT
START
BIT
NON-DISPLAY
CONTROL
CHARACTER
(7 BITS
LSB FIRST)
ODD
PARITY
BIT
DISPLAY
CONTROL
CHARACTER
(7 BITS
LSB FIRST)
ODD
PARITY
BIT
Figure 8.56. Closed Captioning Midrow Code Format. Miscellaneous control codes may also be
transmitted in place of the midrow control code.
Non-display Control Byte Display Control Byte
D6 D5 D4 D3 D2 D1 D0 D6 D5 D4 D3 D2 D1 D0
0 0 1 CH 1 0 F 0 1 0
0 0 1 CH 1 1 1 0 1 0
CH: “0” = data channel 1, “1” = data channel 2 F: “0” = line 21, “1” = line 284
Note: “flash on” blanks associated characters for 0.25 seconds once per second.
Table 8.30. Closed Captioning Miscellaneous Control Codes.
Command
0 0 0 0 resume caption loading
0 0 0 1 backspace
0 0 1 0 reserved
0 0 1 1 reserved
0 1 0 0 delete toendof row
0 1 0 1 roll-up captions,2 rows
0 1 1 0 roll-up captions,3 rows
0 1 1 1 roll-up captions,4 rows
1 0 0 0 flash on
1 0 0 1 resume direct captioning
1 0 1 0 textrestart
1 0 1 1 resume text display
1 1 0 0 erase displayedmemory
1 1 0 1 carriage return
1 1 1 0 erase nondisplayedmemory
1 1 1 1 end of caption (flip memories)
0 0 0 1 tab offset(1 column)
0 0 1 0 taboffset(2 columns)
0 0 1 1 taboffset(3 columns)

LINE 43
LINE 306
LINE 44
LINE 307
LINE 45
LINE 308
LINE 46
LINE 309
LINE 47
LINE 310
LINE 48
LINE 311
LINE 49
LINE 312
LINE 50
LINE 313
LINE 51
LINE 314
LINE 52
LINE 315
LINE 53
LINE 316
LINE 54
LINE 317
LINE 55
LINE 318
BLANK DOT
CHARACTER DOT
UNDERLINE
Figure 8.57. Typical 16×26 Closed Captioning Character Cell Format for Row 1.
DOT
ROW
0
2
4
6
8
10
12
14
16
18
20
22
24
VBI Data 343

344 Chapter 8: NTSC, PAL, and SECAM Overview
Nondisplay Control Byte Display Control Byte Special
Characters
D6 D5 D4 D3 D2 D1 D0 D6 D5 D4 D3 D2 D1 D0
0 0 1 CH 0 0 1 0 1 1
D6 D5 D4 D3
0100
0101
0110
0111
1000
0 0 0 0 ®
0 0 0 1 °
0 0 1 0 1/2
0 0 1 1 ¿
0 1 0 0
0 1 0 1 ¢
0 1 1 0 £
0 1 1 1 music note
1 0 0 0 à
1 0 0 1 transparentspace
1 0 1 0 è
1 0 1 1 â
1 1 0 0 ê
1 1 0 1 î
1 1 1 0 ô
1 1 1 1 û
D2 D1 D0
000 ( 0 8 @ H P X ú h p x
001 ! ) 1 9 A I Q Y a i q y
010 “ á 2 : B J R Z b j r z
011 # + 3 ; C K S [ c k s ç
100 $ , 4 < D L T é d l t ÷
101 % – 5 = E M U ] e m u Ñ
110 & . 6 > F N V í f n v ñ
111 ‘ / 7 ? G O W ó g o w ■
Table 8.31. Closed Captioning Basic Character Set.
1001
1010
1011
1100
1101
1110
1111

Non-display Control Byte Display Control Byte
D6 D5 D4 D3 D2 D1 D0 D6 D5 D4 D3 D2 D1 D0
T: “0” =opaque,“1” = semi-transparent CH: “0” = data channel 1, “1” = data channel 2
Underline resides on dot rows 22 and 23, and covers the entire column width.
Table 8.32. Closed Captioning Optional Attribute Codes.
If a decoder doesn’t support semitransparent
colors, the opaque colors may be used
instead. If a specific background color isn’t
supported by a decoder, it should default to the
black background color. However, if the black
foreground color is supported in a decoder, all
the background colors should be implemented.
A background attribute appears as a standard
space on the display, and the attribute
remains in effect until the end of the row or
until another background attribute is received.
The foreground attributes provide an
eighth color (black) as a character color. As
with midrow codes, a foreground attribute
code turns off italics and blinking, and the
least significant bit controls underlining.
VBI Data 345
Background
Attribute
0 0 0
white
0 0 1 green
0 1 0 blue
0 0 1 CH 0 0 0 0 1 0
0
1
1
0
1
0
T
cyan
red
1 0 1 yellow
1 1 0 magenta
1 1 1 black
0 0 1 CH 1 1 1 0 1 0 1 1 0 1 transparent
D6 D5 D4 D3 D2 D1 D0 D6 D5 D4 D3 D2 D1 D0
0 0 1 CH 1 1 1 0 1 0 1 1 1
Foreground
Attribute
0 black
1 black underline
Background and foreground attribute
codes have an automatic backspace for backward
compatibility with current decoders.
Thus, an attribute must be preceded by a standard
space character. Standard decoders display
the space and ignore the attribute.
Extended decoders display the space, and on
receiving the attribute, backspace, then display
a space that changes the color and opacity.
Thus, text formatting remains the same
regardless of the type of decoder.
Optional Closed Group Extensions
To support custom features and characters not
defined by the standards, the EIA/CEG maintains
a set of code assignments requested by
various caption providers and decoder manu-

346 Chapter 8: NTSC, PAL, and SECAM Overview
facturers. These code assignments (currently
used to select various character sets) are not
compatible with caption decoders in the United
States and videos using them should not be
distributedintheU.S.market.
Closed group extensions require two
bytes. Table 8.33 lists the currently assigned
closed group extensions to support captioning
in the Asian languages.
Optional Extended Characters
An additional 64 accented characters (eight
character sets of eight characters each) may
be supported by decoders, permitting the display
of other languages such as Spanish,
French, Portuguese, German, Danish, Italian,
Finnish, and Swedish. If supported, these
accented characters are available in all caption
and text modes.
Non-display Control Byte Display Control Byte
D6 D5 D4 D3 D2 D1 D0 D6 D5 D4 D3 D2 D1 D0
0 0 1 CH 1 1 1 0 1 0
CH: “0” = data channel 1, “1” = data channel 2
Each of the extended characters incorporates
an automatic backspace for backward
compatibility with current decoders. Thus, an
extended character must be preceded by the
standard ASCII version of the character. Standard
decoders display the ASCII character and
ignore the accented character. Extended
decoders display the ASCII character, and on
receiving the accented character, backspace,
then display the accented character. Thus, text
formatting remains the same regardless of the
type of decoder.
Extended characters require two bytes.
The first byte is 12 H or 13 H for data channel
one (1A H or 1B H for data channel two), followed
by a value of 20 H –3F H .
Table 8.33. Closed Captioning Optional Closed Group Extensions.
Background
Attribute
0 1 0 0
standard character
set (normal size)
0 1 0 1
standard character
set (double size)
0 1 1 0
first private
character set
0 1 1 1
second private
character set
People’s Republic
1 0 0 0 of China character
set (GB 2312)
Korean Standard
1 0 0 1
character set
(KSC 5601-1987)
1 0 1 0 first registered character set

Extended Data Ser vices
Line 284 may contain extended data service
information, interleaved with the caption and
text information, as bandwidth is available. In
this case, control codes are not transmitted
twice, as they may be for the caption and text
services.
Information is transmitted as packets and
operates as a separate unique data channel.
Data for each packet may or may not be contiguous
and may be separated into subpackets
that can be inserted anywhere space is available
in the line 284 information stream.
There are four types of extended data characters:
Control: Control characters are used as a
mode switch to enable the extended data
mode. They are the first character of two and
have a value of 01 F to 0F H .
Type: Type characters follow the control
character (thus, they are the second character
of two) and identify the packet type. They have
a value of 01 F to 0F H .
Checksum: Checksum characters always
follow the “end of packet” control character.
Thus, they are the second character of two and
have a value of 00 F to 7F H .
Informational: These characters may be
ASCII or non-ASCII data. They are transmitted
in pairs up to and including 32 characters. A
NUL character (00 H) is used to ensure pairs of
characters are always sent.
Control Characters
Table8.34liststhecontrolcodes.Thecurrent
class describes a program currently being
transmitted. The future class describes a pro-
VBI Data 347
gram to be transmitted later. It contains the
same information and formats as the current
class. The channel class describes non-program-specific
information about the channel.
The miscellaneous class describes miscellaneous
information. The public class transmits
data or messages of a public service nature.
The undefined class is used in proprietary systems
for whatever that system wishes.
Type Characters (Current, Future Class)
Program Identification Number (01 H )
This packet uses four characters to specify the
program start time and date relative to Coordinated
Universal Time (UTC). The format is
shown in Table 8.35.
Minutes have a range of 0–59. Hours have
arangeof0–23. Dates have a range of 1–31.
Months have a range of 1–12. “T” indicates if a
program is routinely tape delayed for the
Mountain and Pacific time zones. The “D,” “L,”
and “Z” bits are ignored by the decoder.
Program Length (02 H )
This packet has 2, 4, or 6 characters and indicates
the scheduled length of the program and
elapsed time for the program. The format is
shown in Table 8.36.
Minutes and seconds have a range of 0–59.
Hours have a range of 0–63.
Program Name (03 H )
This packet contains 2–32 ASCII characters
that specify the title of the program.
Program Type (04 H )
This packet contains 2–32 characters that specify
the type of program. Each character is
assigned a keyword, as shown in Table 8.37.

348 Chapter 8: NTSC, PAL, and SECAM Overview
Control
Code
01H 02H 03H 04H 05H 06H 07H 08H 09H 0AH 0BH 0CH 0DH 0EH Function Class
start
continue
start
continue
start
continue
start
continue
start
continue
start
continue
start
continue
current
future
channel
miscellaneous
public service
reserved
undefined
0F H end all
Table 8.34. EIA-608 Control Codes.
D6 D5 D4 D3 D2 D1 D0 Character
1 m5 m4 m3 m2 m1 m0 minute
1 D h4 h3 h2 h1 h0 hour
1 L d4 d3 d2 d1 d0 date
1 Z T m3 m2 m1 m0 month
Table 8.35. EIA-608 Program Identification Number Format.

Code
(hex)
20
21
22
23
24
25
26
27
28
29
2A
2B
2C
2D
2E
2F
50
51
52
53
54
55
56
57
58
59
5A
5B
5C
5D
5E
5F
D6 D5 D4 D3 D2 D1 D0 Character
1 m5 m4 m3 m2 m1 m0 length,minute
1 h5 h4 h3 h2 h1 h0 length,hour
1 m5 m4 m3 m2 m1 m0 elapsed time,minute
1 h5 h4 h3 h2 h1 h0 elapsed time,hour
1 s5 s4 s3 s2 s1 s0 elapsed time,second
0 0 0 0 0 0 0 null character
Keyword
education
entertainment
movie
news
religious
sports
other
action
advertisement
animated
anthology
automobile
awards
baseball
basketball
bulletin
hockey
home
horror
information
instruction
international
interview
language
legal
live
local
math
medical
meeting
military
miniseries
Table 8.36. EIA-608 Program Length Format.
Code
(hex)
30
31
32
33
34
35
36
37
38
39
3A
3B
3C
3D
3E
3F
60
61
62
63
64
65
66
67
68
69
6A
6B
6C
6D
6E
6F
Keyword
business
classical
college
combat
comedy
commentary
concert
consumer
contemporary
crime
dance
documentary
drama
elementary
erotica
exercise
music
mystery
national
nature
police
politics
premiere
prerecorded
product
professional
public
racing
reading
repair
repeat
review
Table 8.37. EIA-608 Program Types.
Code
(hex)
40
41
42
43
44
45
46
47
48
49
4A
4B
4C
4D
4E
4F
70
71
72
73
74
75
76
77
78
79
7A
7B
7C
7D
7E
7F
VBI Data 349
Keyword
fantasy
farm
fashion
fiction
food
football
foreign
fund raiser
game/quiz
garden
golf
government
health
high school
history
hobby
romance
science
series
service
shopping
soap opera
special
suspense
talk
technical
tennis
travel
variety
video
weather
western

350 Chapter 8: NTSC, PAL, and SECAM Overview
Program Rating (05 H )
This packet, commonly referred to regarding
the ”v” chip, contains the information shown in
Table 8.38 to indicate the program rating.
V indicates if violence is present. S indicates
if sexual situations are present. L indicates
if adult language is present. D indicates if
sexually suggestive dialog is present.
Program Audio Services (06 H )
This packet contains two characters as shown
in Table 8.39 to indicate the program audio services
available.
Program Caption Services (07 H )
This packet contains 2–8 charactersasshown
in Table 8.40 to indicate the program caption
services available. L2–L0 are coded as shown
in Table 8.39.
Copy Generation Management System (08 H )
This CGMS-A (Copy Generation Management
System—Analog) packet contains 2 charactersasshowninTable8.41.
InthecasewhereeitherB3orB4isa“0”,
there is no Analog Protection System (B1 and
B2 are “0”). B0 is the analog source bit.
Program Aspect Ratio (09 H )
This packet contains two or four characters as
shown in Table 8.42 to indicate the aspect ratio
of the program.
S0–S5 specify the first line containing
active picture information. The value of S0–S5
is calculated by subtracting 22 from the first
line containing active picture information. The
valid range for the first line containing active
picture information is 22–85.
E0–E5 specify the last line containing
active picture information. The last line containing
active video is calculated by subtracting
the value of E0–E5 from 262. The valid range
for the last line containing active picture information
is 199–262.
When this packet contains all zeros for
both characters, or the packet is not detected,
an aspect ratio of 4:3 is assumed.
The Q0 bit specifies whether the video is
squeezed (“1”) or normal (“0”). Squeezed
video (anamorphic) is the result of compressing
a 16:9 aspect ratio picture into a 4:3 aspect
ratio picture without cropping side panels.
The aspect ratio is calculated as follows:
320 / (E – S) : 1
Program Description (10 H –17 H )
This packet contains 1–8 packet rows, with
each packet row containing 0–32 ASCII characters.
A packet row corresponds to a line of text
on the display.
Each packet is used in numerical
sequence, and if a packet contains no ASCII
characters, a blank line will be displayed.
Type Characters (Channel Class)
Network Name (01 H )
This packet uses 2–32 ASCII characters to
specify the network name.
Network Call Letters (02 H )
This packet uses four or six ASCII characters
to specify the call letters of the channel. When
six characters are used, they reflect the overthe-air
channel number (2–69) assigned by the
FCC. Single-digit channel numbers are preceded
by a zero or a null character.
Channel Tape Delay (03 H )
This packet uses two characters to specify the
number of hours and minutes the local station
typically delays network programs. The format
of this packet is shown in Table 8.43.

D6 D5 D4 D3 D2 D1 D0 Character
1 D / a2 a1 a0 r2 r1 r0 MPAA movie rating
1 V S L/ a3 g2 g1 g0 TV rating
VBI Data 351
r2–r0: Movie Rating g2–g0: USA TV Rating a3–a0: xxx0 MPAA movie rating
000 not applicable 000 not rated LD01 USA TV rating
001 G 001 TV-Y 0011 Canadian English TV rating
010 PG 010 TV-Y7 0111 Canadian French TV rating
011 PG-13 011 TV-G 1011 reserved
100 R 100 TV-PG 1111 reserved
101 NC-17 101 TV-14
110 X 110 TV-MA
111 not rated 111 not rated
g2–g0: Canadian English TV Rating g2–g0: Canadian French TV Rating
000 exempt 000 exempt
001 C 001 G
010 C8 + 010 8 ans +
011 G 011 13 ans +
100 PG 100 16 ans +
101 14 + 101 18 ans +
110 18 + 110 reserved
111 reserved 111 reserved
Table 8.38. EIA-608 and EIA-744 Program Rating Format.
D6 D5 D4 D3 D2 D1 D0 Character
1 L2 L1 L0 T2 T1 T0 main audio program
1 L2 L1 L0 S2 S1 S0 secondaudio program (SAP)
L2–L0: 000 unknown T2–T0: 000 unknown S2–S0: 000 unknown
001 english 001 mono 001 mono
010 spanish 010 simulated stereo 010 video descriptions
011 french 011 true stereo 011 non-program audio
100 german 100 stereo surround 100 special effects
101 italian 101 data service 101 data service
110 other 110 other 110 other
111 none 111 none 111 none
Table 8.39. EIA-608 Program Audio Services Format.

352 Chapter 8: NTSC, PAL, and SECAM Overview
D6 D5 D4 D3 D2 D1 D0 Character
1 L2 L1 L0 F C T service code
FCT: 000 line 21, data channel 1 captioning
001 line 21, data channel 1 text
010 line 21, data channel 2 captioning
011 line 21, data channel 2 text
100 line 284, data channel 1 captioning
101 line 284, data channel 1 text
110 line 284, data channel 2 captioning
111 line 284, data channel 2 text
Table 8.40. EIA-608 Program Caption Services Format.
D6 D5 D4 D3 D2 D1 D0 Character
1 0 B4 B3 B2 B1 B0 CGMS
0 0 0 0 0 0 0 null
B4–B3 CGMS–A Services:
00 copying permitted without restriction
01 condition not to be used
10 one generation copy allowed
11 no copying permitted
B2–B1 Analog Protection Ser vices:
00 no pseudo-sync pulse
01 pseudo-sync pulse on; color striping off
10 pseudo-sync pulse on; 2-line color striping on
11 pseudo-sync pulse on; 4-line color striping on
Table 8.41. EIA-608 and EIA IS–702 CGMS–A Format.

D6 D5 D4 D3 D2 D1 D0 Character
1 S5 S4 S3 S2 S1 S0 start
1 E5 E4 E3 E2 E1 E0 end
1 – – – – – Q0 other
0 0 0 0 0 0 0 null
Table 8.42. EIA-608 Program Aspect Ratio Format.
D6 D5 D4 D3 D2 D1 D0 Character
1 m5 m4 m3 m2 m1 m0 minute
1 – h4 h3 h2 h1 h0 hour
Table 8.43. EIA-608 Channel Tape Delay Format.
D6 D5 D4 D3 D2 D1 D0 Character
1 m5 m4 m3 m2 m1 m0 minute
1 D h4 h3 h2 h1 h0 hour
1 L d4 d3 d2 d1 d0 date
1 Z T m3 m2 m1 m0 month
1 – – – D2 D1 D0 day
1 Y5 Y4 Y3 Y2 Y1 Y0 year
Table 8.44. EIA-608 Time of Day Format.
VBI Data 353

354 Chapter 8: NTSC, PAL, and SECAM Overview
Minutes have a range of 0–59. Hours have
a range of 0–23. This delay applies to all programs
on the channel that have the “T” bit set
in their Program ID packet (Table 8.35).
Type Characters (Miscellaneous Class)
Time of Day (01 H )
This packet uses six characters to specify the
current time of day, month, and date relative to
Coordinated Universal Time (UTC). The format
is shown in Table 8.44.
Minutes have a range of 0–59. Hours have
a range of 0–23. Dates have a range of 1–31.
Months have a range of 1–12. Days have a
range of 1 (Sunday) to 7 (Saturday). Years
have a range of 0–63 (added to 1990).
“T” indicates if a program is routinely tape
delayed for the Mountain and Pacific time
zones. “D” indicates whether daylight savings
time currently is being observed. “L” indicates
whether the local day is February 28th or 29th
when it is March 1st UTC. “Z” indicates
whether the seconds should be set to zero (to
allow calibration without having to transmit the
full 6 bits of seconds data).
Impulse Capture ID (02 H )
This packet carries the program start time and
length, and can be used to tell a VCR to record
this program. The format is shown in Table
8.45.
Start and length minutes have a range of
0–59. Start hours have a range of 0–23; length
hours have a range of 0–63. Dates have a range
of 1–31. Months have a range of 1–12. “T” indicates
if a program is routinely tape delayed for
the Mountain and Pacific time zones. The “D,”
“L.” and “Z” bits are ignored by the decoder.
Supplemental Data Location (03 H )
This packet uses 2–32 characters to specify
other lines where additional VBI data may be
found. Table 8.46 shows the format.
“F” indicates field one (“0”) orfieldtwo
(“1”). N may have a value of 7–31, and indicates
a specific line number.
Local Time Zone (04 H )
This packet uses two characters to specify the
viewer time zone and whether the locality
observes daylight savings time. The format is
shown in Table 8.47.
Hours have a range of 0–23. This is the
nominal time zone offset, in hours, relative to
UTC. “D” is a “1” when the area is using daylight
savings time.
Out-of-Band Channel Number (40 H )
This packet uses two characters to specify a
channel number to which all subsequent outof-band
packets refer. This is the CATV channel
number to which any following out-of-band
packets belong to. The format is shown in
Table 8.48.
Closed Captioning for Europe
Closed captioning may be also used with PAL
videotapes and laserdiscs in Europe, present
during the blanked active line-time portion of
lines 22 and 335.
The data format, amplitudes, and rise and
fall times are the same as for closed captioning
in the United States. The timing, as shown in
Figure 8.58, is slightly different due to the PAL
horizontal timing. Older closed captioning
decoders designed for use only with NTSC systems
may not work due to these timing differences.

D6 D5 D4 D3 D2 D1 D0 Character
1 m5 m4 m3 m2 m1 m0 start,minute
1 D h4 h3 h2 h1 h0 start, hour
1 L d4 d3 d2 d1 d0 start, date
1 Z T m3 m2 m1 m0 start,month
1 m5 m4 m3 m2 m1 m0 length,minute
1 h5 h4 h3 h2 h1 h0 length,hour
Table 8.45. EIA-608 Impulse Capture ID Format.
D6 D5 D4 D3 D2 D1 D0 Character
1 F N4 N3 N2 N1 N0 location
Table 8.46. EIA-608 Supplemental Data Format.
D6 D5 D4 D3 D2 D1 D0 Character
1 D h4 h3 h2 h1 h0 hour
0 0 0 0 0 0 0 null
Table 8.47. EIA-608 Local Time Zone Format.
D6 D5 D4 D3 D2 D1 D0 Character
1 c5 c4 c3 c2 c1 c0 channel low
1 c11 c10 c9 c8 c7 c6 channel high
Table 8.48. EIA-608 Out-of-Band Channel Number Format.
VBI Data 355

356 Chapter 8: NTSC, PAL, and SECAM Overview
Widescreen Signalling
To facilitate the handling of various aspect
ratios of program material received by TVs, a
widescreen signalling (WSS) system has been
developed. This standard allows a WSSenhanced
16:9 TV to display programs in their
correct aspect ratio.
625-Line PAL and SECAM Systems
625-line PAL and SECAM systems are based
on ITU-R BT.1119 and ETSI EN 300294. For
YPbPr and S-video interfaces, WSS is present
on the Y signal. For analog RGB interfaces,
WSS is present on all three signals.
The Analog Copy Generation Management
System (CGMS-A) is also supported by the
WSS signal.
BLANK LEVEL
SYNC LEVEL
50 ±2 IRE
43 IRE
10.5 ± 0.25 µS
4.43 MHZ
COLOR BURST
(10 CYCLES)
10.00 ± 0.25 µS
13.0 µS
7 CYCLES
OF 0.500 MHZ
(CLOCK RUN–IN)
Data Timing
The first part of line 23 is used to transmit the
WSS information, as shown in Figure 8.59.
The clock frequency is 5 MHz (±100 Hz).
The signal waveform should be a sine-squared
pulse, with a half-amplitude duration of 200 ±10
ns. The signal amplitude is 500 mV ±5%.
The NRZ data bits are processed by a biphase
code modulator, such that one data
period equals 6 elements at 5 MHz.
Data Content
The WSS consists of a run-in code, a start
code, and 14 bits of data, as shown in Table
8.49.
TWO 7–BIT + PARITY
ASCII CHARACTERS
(DATA)
27.5 µS 34.0 µS
S
T
A
R
T
D0–D6 P D0–D6
A
R
I
T
Y
Figure 8.58. (B, D, G, H, I) PAL Line 22 and Line 335 Closed Captioning Timing.
P
A
R
I
T
Y
240–288 NS
RISE / FALL
TIMES
(2T BAR
SHAPING)

Run-In
The run-in consists of 29 elements at 5 MHz of
a specific sequence, shown in Table 8.49.
Start Code
The start code consists of 24 elements at 5
MHz of a specific sequence, shown in Table
8.49.
Group A Data
The group A data consists of 4 data bits that
specify the aspect ratio. Each data bit generates
6 elements at 5 MHz. Data bit b0 is the
LSB.
Table 8.50 lists the data bit assignments
andusage.Thenumberofactivelineslistedin
Table 8.50 are for the exact aspect ratio (a =
1.33, 1.56, or 1.78).
The aspect ratio label indicates a range of
possible aspect ratios (a) and number of active
lines:
4:3 a ≤ 1.46 527–576
14:9 1.46 < a ≤ 1.66 463–526
16:9 1.66 < a ≤ 1.90 405–462
>16:9 a > 1.90 < 405
BLANK LEVEL
SYNC LEVEL
500 MV ±5%
43 IRE
COLOR
BURST
RUN
IN
29
5 MHZ
ELEMENTS
START
CODE
24
5 MHZ
ELEMENTS
11.00 ± 0.25 µS 27.4 µS
DATA
(B0 - B13)
84
5 MHZ
ELEMENTS
FIgure 8.59. PAL Line 23 WSS Timing.
VBI Data 357
To allow automatic selection of the display
mode, a 16:9 receiver should support the following
minimum requirements:
Case 1: The 4:3 aspect ratio picture should
be centered on the display, with black bars
on the left and right sides.
Case 2: The 14:9 aspect ratio picture
should be centered on the display, with
black bars on the left and right sides. Alternately,
the picture may be displayed using
the full display width by using a small (typically
8%) horizontal geometrical error.
Case 3: The 16:9 aspect ratio picture
should be displayed using the full width of
the display.
Case 4: The >16:9 aspect ratio picture
should be displayed as in Case 3 or use the
full height of the display by zooming in.
Group B Data
The group B data consists of four data bits that
specify enhanced services. Each data bit gen-
190–210 NS
RISE / FALL
TIMES
(2T BAR
SHAPING)

358 Chapter 8: NTSC, PAL, and SECAM Overview
run-in
start code
group A
(aspect ratio)
group B
(enhanced services)
group C
(subtitles)
group D
(reserved)
b3,b2,b1,b0
Aspect Ratio
Label
29 elements
at 5 MHz
24 elements
at 5 MHz
24 elements
at 5 MHz
“0” = 000 111
“1” = 111 000
24 elements
at 5 MHz
“0” = 000 111
“1” = 111 000
18 elements
at 5 MHz
“0” = 000 111
“1” = 111 000
18 elements
at 5 MHz
“0” = 000 111
“1” = 111 000
1 1111 0001 1100 0111 0001 1100 0111
(1F1C 71C7 H)
0001 1110 0011 1100 0001 1111
(1E 3C1F H)
b0,b1,b2,b3
b4,b5,b6,b7
(b7 = “0” since reserved)
b8, b9, b10
b11, b12, b13
Table 8.49. PAL WSS Information.
Format
Position On
4:3 Display
Active
Lines
Minimum
Requirements
1000 4:3 full format – 576 case 1
0001 14:9 letterbox center 504 case 2
0010 14:9 letterbox top 504 case 2
1011 16:9 letterbox center 430 case 3
0100 16:9 letterbox top 430 case 3
1101 > 16:9 letterbox center – case 4
1110 14:9 full format center 576 –
0111 16:9
full format
(anamorphic)
– 576 –
Table 8.50. PAL WSS Group A (Aspect Ratio) Data Bit Assignments and Usage.

erates six elements at 5 MHz. Data bit b4 is the
LSB. Bits b5 and b6 are used for PALplus.
b4: mode
0 camera mode
1 film mode
b5: color encoding
0 normal PAL
1 Motion Adaptive ColorPlus
b6: helper signals
0 not present
1 present
Group C Data
The group C data consists of three data bits
that specify subtitles. Each data bit generates
six elements at 5 MHz. Data bit b8 is the LSB.
b8: teletext subtitles
0 no
1 yes
b10, b9: open subtitles
00 no
01 inside active picture
10 outsideactivepicture
11 reserved
Group D Data
The group D data consists of three data bits
that specify surround sound and copy protection.
Each data bit generates six elements at 5
MHz. Data bit b11 is the LSB.
b11: surround sound
0 no
1 yes
b12: copyright
0 no copyright asserted or unknown
1 copyright asserted
b13: copy protection
0 copying not restricted
1 copying restricted
VBI Data 359
525-Line NTSC Systems
EIA-J CPR-1204 and IEC 61880 define a widescreen
signalling standard for NTSC systems.
For YPbPr and S-video interfaces, WSS is
present on the Y signal. For analog RGB interfaces,
WSS is present on all three signals.
Data Timing
Lines20and283areusedtotransmittheWSS
information, as shown in Figure 8.60.
The clock frequency is F SC /8 or about
447.443 kHz; F SC is the color subcarrier frequency
of 3.579545 MHz. The signal waveform
should be a sine-squared pulse, with a halfamplitude
duration of 2.235 µs ±50 ns. The signal
amplitude is 70 ±10 IRE for a “1”, and0±5
IRE for a “0”.
Data Content
The WSS consists of 2 bits of start code, 14 bits
ofdata,and6bitsofCRC,asshowninTable
8.51. The CRC used is X 6 +X+1,allpresetto
“1”.
Start Code
The start code consists of a “1” data bit followed
by a “0” data bit, as shown in Table 8.51.
Word 0 Data
Word 0 data consists of 2 data bits:
b1, b0:
00 4:3 aspect ratio normal
01 16:9 aspect ratio anamorphic
10 4:3 aspect ratio letterbox
11 reserved

360 Chapter 8: NTSC, PAL, and SECAM Overview
BLANK LEVEL
SYNC LEVEL
70 ±10 IRE
40 IRE
COLOR
BURST
START
CODE
"1"
START
CODE
"0"
DATA
(B0 - B19)
11.20 ± 0.30 µS 49.1 ± 0.44 µS
FIgure 8.60. NTSC Line 20 and Line 283 WSS Timing.
start code “1”
start code “0”
word 0 b0, b1
word 1 b2, b3, b4, b5
word 2 b6, b7, b8, b9, b10, b11, b12, b13
CRC b14, b15, b16, b17, b18, b19
Table 8.51. NTSC WSS Data Bit Assignments and Usage.
2235 ±50 NS
RISE / FALL
TIMES
(2T BAR
SHAPING)

Word 1 Data
Word 1 data consists of 4 data bits:
b5, b4, b3, b2:
0000 copy control information
1111 default
Copy control information is transmitted in
Word2datawhenWord1datais“0000”. When
copy control information is not to be transferred,
Word 1 data must be set to the default
value “1111”.
Word 2 Data
Word 2 data consists of 14 data bits. When
Word 1 data is “0000”, Word 2 data consists of
copy control information. Word 2 copy control
data must be transferred at the rate of two or
more frames per two seconds.
Bits b6 and b7 specify the copy generation
management system in an analog signal
(CGMS-A). CGMS-A consists of two bits of digital
information:
b7, b6:
00 copying permitted
01 one copy permitted
10 reserved
11 no copying permitted
Bits b8 and b9 specify the operation of the
the Macrovision copy protection signals added
to the analog NTSC video signal:
b9, b8:
00 PSP off
01 PSP on, 2-line split burst on
10 PSP on, split burst off
11 PSP on, 4-line split burst on
PSP is the Macrovision pseudo-sync pulse
operation.
VBI Data 361
Split burst operation inverts the normal
phase of the first half of the color burst signal
on specified scan lines in a normal analog
video signal. The color burst of four successive
lines of every 21 lines is modified, beginning at
lines 24 and 297 (four-line split burst system)
or of two successive lines of every 17 lines,
beginning at lines 30 and 301 (two-line split
burst system). The color burst on all other
linesisnotmodified.
Bit b10 specifies whether the source originatedfromananalogpre-recordedmedium.
b10:
0 not analog pre-recorded medium
1 analog pre-recorded medium
Bits b11, b12, and b13 are reserved and are
“000”.
Teletext
Teletext allows the transmission of text, graphics,
and data. Data may be transmitted on any
line, although the VBI interval is most commonly
used. The teletext standards are specified
by ETSI ETS 300706, ITU-R BT.653 and
EIA–516.
For YPbPr and S-video interfaces, teletext
is present on the Y signal. For analog RGB
interfaces, teletext is present on all three signals.
There are many systems that use the teletext
physical layer to transmit proprietary
information. The advantage is that teletext has
already been approved in many countries for
broadcast, so certification for a new transmission
technique is not required.
The data rate for teletext is much higher
than that used for closed captioning, approachingupto7Mbpsinsomecases.Therefore,
ghost cancellation is needed to reliably recover
the transmitted data.

362 Chapter 8: NTSC, PAL, and SECAM Overview
There are seven teletext systems, as
shown in Table 8.52. EIA–516, also referred to
as NABTS (North American Broadcast Teletext
Specification), is used in the United States,
and is an expansion of the BT.653 525-line system
C standard.
System A:
Columbia India
France
System B:
Australia Netherlands
Belgium New Zealand
China Norway
Denmark Poland
Egypt Singapore
Finland South Africa
Germany Spain
Italy Sweden
Jordan Turkey
Kuwait United Kingdom
Malaysia Yugoslavia
Morocco
System C:
Brazil United States
Canada
System D:
Japan
Figure 8.61 illustrates the teletext data on a
scan line. If a line normally contains a color
burst signal, it will still be present if teletext
data is present. The 16 bits of clock run-in (or
clock sync) consists of alternating “1’s” and
“0’s”.
Figures 8.62 and 8.63 illustrates the structure
of teletext systems B and C, respectively.
System B Teletext Over view
Since teletext System B is the most popular
teletext format, a basic overview is presented
here.
A teletext service typically consists of
pages, with each page corresponding to a
screen of information. The pages are transmitted
one at time, and after all pages have been
Parameter System A System B System C System D
bit rate (Mbps) 6.203125
625-Line Video Systems
6.9375 5.734375 5.6427875
data amplitude 67 IRE 66 IRE 70 IRE 70 IRE
data per line 40 bytes 45 bytes 36 bytes 37 bytes
525-Line Video Systems
bit rate (Mbps) – 5.727272 5.727272 5.727272
data amplitude – 70 IRE 70 IRE 70 IRE
data per line – 37 bytes 36 bytes 37 bytes
Table 8.52. Summary of Teletext Systems and Parameters.

transmitted, the cycle repeats, with a typical
cycle time of about 30 seconds. However, the
broadcaster may transmit some pages more
frequently than others, if desired.
The teletext service is usually based on up
to eight magazines (allowing up to eight independent
teletext services), with each magazine
containing up to 100 pages. Magazine 1 uses
page numbers 100–199, magazine 2 uses page
numbers 200–299, etc. Each page may also
have sub-pages, used to extend the number of
pages within a magazine.
Each page contains 24 rows, with up to 40
characters per row. A character may be a letter,
number, symbol, or simple graphic. There are
also control codes to select colors and other
attributes such as blinking and double height.
In addition to teletext information, the teletext
protocol may be used to transmit other
information, such as subtitling, program delivery
control (PDC), and private data.
BLANK LEVEL
SYNC LEVEL
COLOR
BURST
CLOCK
RUN-IN
FIgure 8.61. Teletext Line Format.
DATA AND ADDRESS
VBI Data 363
Subtitling
Subtitling is similar to the closed captioning
used in the United States. “Open” subtitles are
the insertion of text directly into the picture
prior to transmission. “Closed” subtitles are
transmitted separately from the picture. The
transmission of closed subtitles in the UK use
teletext page 888. In the case where multiple
languages are transmitted using teletext, separate
pages are used for each language.
Program Delivery Control (PDC)
Program Delivery Control (defined by ETSI
ETS 300231 and ITU-R BT.809) is a system that
controls VCR recording using teletext information.
The VCR can be programmed to look for
andrecordvarioustypesofprogramsoraspecific
program. Programs are recorded even if
the transmission time changes for any reason.
There are two methods of transmitting
PDC information via teletext: methods A and
B.

364 Chapter 8: NTSC, PAL, and SECAM Overview
PAGE ADDRESS
(1 BYTE)
MAGAZINE / PACKET ADDRESS
(2 BYTES)
BYTE SYNC
(1 BYTE)
CLOCK SYNC
(2 BYTES)
TELETEXT
PACKET 27
HEADER PACKET
NEXT HEADER PACKET
DATA BLOCK
DATA PACKET
NEXT HEADER PACKET
LAST PACKET OF PAGE
PACKET 26
PACKET 28
PAGE
PACKET 27 DATA
HEADER PACKET
GROUP
APPLICATION LAYER
PRESENTATION LAYER
SESSION LAYER
TRANSPORT LAYER
NETWORK LAYER
LINK LAYER
DATA UNIT PHYSICAL LAYER
FIgure 8.62. Teletext System B Structure.

RECORD HEADER
DATA GROUP HEADER
(8 BYTES)
P HEADER
(5 BYTES)
BYTE SYNC
(1 BYTE)
CLOCK SYNC
(2 BYTES)
TELETEXT
ITU-T T.101, ANNEX D
RECORD 1
DATA GROUP 1
DATA BLOCK
DATA PACKET
RECORD N
DATA GROUP N
S (1 BYTE)
APPLICATION LAYER
PRESENTATION LAYER
SESSION LAYER
TRANSPORT LAYER
NETWORK LAYER
LINK LAYER
DATA UNIT PHYSICAL LAYER
FIgure 8.63. Teletext System C Structure.
VBI Data 365

366 Chapter 8: NTSC, PAL, and SECAM Overview
Method A places the data on a viewable
teletext page, and is usually transmitted on
scan line 16. This method is also known as the
Video Programming System (VPS).
Method B places the data on a hidden
packet (packet 26) in the teletext signal. This
packet 26 data contains the data on each program,
including channel, program data, and
start time.
Data Broadcasting
Data broadcasting may be used to transmit
information to private receivers. Typical applications
include real-time financial information,
airport flight schedules for hotels and travel
agents, passenger information for railroads,
software upgrades, etc.
Packets 0–23
A typical teletext page uses 24 packets, numbered
0–23, that correspond to the 24 rows on
a displayed page. Packet 24 can add a status
rowatthebottomforuserprompting.Foreach
packet, three bits specify the magazine
address (1–8), and five bits specify the row
address (0–23). The magazine and row
address bits are Hamming error protected to
permit single-bit errors to be corrected.
To save bandwidth, the whole address isn’t
sent with all packets. Only packet 0 (also called
the header packet) has all the address information
such as row, page, and magazine address
data. Packets 1–28 contain information that is
part of the page identified by the most recent
packet 0 of the same magazine.
The transmission of a page starts with a
header packet. Subsequent packets with the
same magazine address provide additional
data for that page. These packets may be transmitted
in any order, and interleaved with packets
from other magazines. A page is
considered complete when the next header
packet for that magazine is received.
The general format for packet 0 is:
clock run-in 2 bytes
framing code 1 byte
magazine and row address 2 bytes
page number 2 bytes
subcode 4 bytes
control codes 2 bytes
display data 32 bytes
The general format for packets 1–23 is:
clock run-in 2 bytes
framing code 1 byte
magazine and row address 2 bytes
display data 40 bytes
Packet 24
This packet defines an additional row for user
prompting. Teletext decoders may use the data
in packet 27 to react to prompts in the packet
24 display row.
Packet 25
This packet defines a replacement header line.
If present, the 40 bytes of data are displayed
instead of the channel, page, time, and date
from packet 8.30.
Packet 26
Packet 26 consists of:
clock run-in 2 bytes
framing code 1 byte
magazine and row address 2 bytes
designation code 1 byte
13 3-byte data groups, each consisting of
7databits
6addressbits
5modebits
6 Hamming bits

There are 15 variations of packet 26,
defined by the designation code. Each of the 13
data groups specify a specific display location
and data relating to that location.
This packet is also used to extend the
addressable range of the basic character set in
order to support other languages, such as Arabic,
Spanish, Hungarian, Chinese, etc.
For PDC, packet 26 contains data for each
program, identifying the channel, program
date, start time, and the cursor position of the
program information on the page. When the
user selects a program, the cursor position is
linked to the appropriate packet 26 preselection
data. This data is then used to program the
VCR. When the program is transmitted, the
program information is transmitted using
packet 8.30 format 2. A match between the preselection
data and the packet 8.30 data turns
the VCR record mode on.
Packet 27
Packet 27 tells the teletext decoder how to
respond to user selections for packet 24. There
may be up to four packet 27s (packets 27/0
through 27/3), allowing up to 24 links. It consists
of:
clock run-in 2 bytes
framing code 1 byte
magazine and row address 2 bytes
designation code 1 byte
link 1 (red) 6 bytes
link 2 (green) 6 bytes
link 3 (yellow) 6 bytes
link 4 (cyan) 6 bytes
link 5 (next page) 6 bytes
link 6 (index) 6 bytes
link control data 1 byte
page check digit 2 bytes
Each link consists of:
7databits
6addressbits
5modebits
6hammingbits
VBI Data 367
This packet contains information linking
the current page to six page numbers (links).
The four colored links correspond to the four
colored Fastext page request keys on the
remote. Typically, these four keys correspond
to four colored menu selections at the bottom
of the display using packet 24. Selection of one
of the colored page request keys results in the
selection of the corresponding linked page.
The fifth link is used for specifying a page
theusermightwanttoseeafterthecurrent
page, such as the next page in a sequence.
The sixth link corresponds to the Fastext
index key on the remote, and specifies the
page address to go to when the index is
selected.
Packets 28 and 29
These are used to define level 2 and level 3
pages to support higher resolution graphics,
additional colors, alternate character sets, etc.
They are similar in structure to packet 26.
Packet 8.30 Format 1
Packet 8.30 (magazine 8, packet 30) isn’t associated
with any page, but is sent once per second.
This packet is also known as the
Television Service Data Packet, or TSDP. It
contains data that notifies the teletext decoder
about the transmission in general and the time.
clock run-in 2 bytes
framing code 1 byte
magazine and row address 2 bytes
designation code 1 byte
initial teletext page 6 bytes
network ID 2 bytes

368 Chapter 8: NTSC, PAL, and SECAM Overview
time offset from UTC 1 byte
date (Modified Julian Day) 3 bytes
UTC time 3 bytes
TV program label 4 bytes
status display 20 bytes
The Designation Code indicates whether
the transmission is during the VBI or full-field.
Initial Teletext Page tells the decoder
which page should be captured and stored on
power-up. This is usually an index or menu
page.
The Network Identification code identifies
the transmitting network.
The TV Program Label indicates the program
label for the current program.
Status Display is used to display a transmission
status message.
Packet 8.30 Format 2
This format is used for PDC recorder control,
and is transmitted once per second per stream.
It contains a program label indicating the start
of each program, usually transmitted about 30
seconds before the start of the program to
allow the VCR to detect it and get ready to
record.
clock run-in 2 bytes
framing code 1 byte
magazine and row address 2 bytes
designation code 1 byte
initial teletext page 6 bytes
label channel ID 1 byte
program control status 1 byte
country and network ID 2 bytes
program ID label 5 bytes
country and network ID 2 bytes
program type 2 bytes
status display 20 bytes
ThecontentisthesameasforFormat1,
except for the 13 bytes of information before
the status display information.
Label channel ID (LCI) identifies each of
up to four PDC streams that may be transmitted
simultaneously.
The Program Control Status (PCS) indicates
real-time status information, such as the
type of analog sound transmission.
The Country and Network ID (CNI) is split
into two groups. The first part specifies the
country and the second part specifies the network.
Program ID Label (PIL) specifies the
month, day, and local time of the start of the
program.
Program Type (PTY) is a code that indicates
an intended audience or a particular
series. Examples are “adult”, “children”,
“music”, “drama”, etc.
Packet 31
Packet 31 is used for the transmission of data
to private receivers. It consists of:
clock run-in 2 bytes
framing code 1 byte
data channel group 1 byte
message bits 1 byte
format type 1 byte
address length 1 byte
address 0–6 bytes
repeat indicator 0–1byte
continuity indicator 0–1byte
data length 0–1byte
user data 28–36 bytes
CRC 2 bytes

ATVEF Interactive Content
ATVEF (Advanced Television Enhancement
Forum) is a standard for creating and delivering
enhanced and interactive programs. The
enhanced content can be delivered over a variety
of mediums—including analog and digital
television broadcasts—using terrestrial, cable,
and satellite networks.
In defining how to create enhanced content,
the ATVEF specification defines the minimum
functionality required by ATVEFcompliant
receivers. To minimize the creation
of new specifications, the ATVEF uses existing
Internet technologies such as HTML and Javascript.
Two additional benefits of doing this are
that there are already millions of pages of
potential content, and the ability to use existing
web-authoring tools.
The ATVEF 1.0 Content Specification mandates
that receivers support, as a minimum,
HTML 4.0, Javascript 1.1, and Cascading Style
Sheets. Supporting additional capabilities,
such as Java and VRML, are optional. This
ensures content is available to the maximum
number of viewers.
For increased capability, a new “tv:”
attribute is added to the HTML. This attribute
enables the insertion of the television program
intothecontent,andmaybeusedinaHTML
document anywhere that a regular image may
be placed. Creating an enhanced content page
that displays the current television channel
anywhere on the display is as easy as inserting
an image in a HTML document.
The specification also defines how the
receiver obtains the content and how it is
informed that enhancements are available. The
latter task is accomplished with triggers.
VBI Data 369
Triggers
Triggers alert receivers to content enhancements,
and contain information about the
enhancements. Among other things, triggers
contain a Universal Resource Locator (URL)
that defines the location of the enhanced content.
Content may reside locally—such as
when delivered over the network and cached
to a local hard drive—oritmayresideonthe
Internet or another network.
Triggers may also contain a human-readable
description of the content. For example, it
maycontainthedescription“Press ORDER to
order this product”, which can be displayed for
the viewer. Triggers also may contain expiration
information, indicating how long the
enhancement should be offered to the viewer.
Lastly, triggers may contain scripts that
trigger the execution of Javascript within the
associated HTML page, to support synchronization
of the enhanced content with the video
signal and updating of dynamic screen data.
Transports
Besides defining how content is displayed, and
how the receiver is notified of new content, the
specification also defines how content is delivered.
Because a receiver may not have an
Internet connection, the specification
describes two models for delivering content.
These two models are called transports, and
the two transports are referred to as Transport
Type A and Transport Type B.
If the receiver has a back-channel (or
return path) to the Internet, Transport Type A
will broadcast the trigger and the content will
be pulled over the Internet.

370 Chapter 8: NTSC, PAL, and SECAM Overview
If the receiver does not have an Internet
connection, Transport Type B provides for
delivery of both triggers and content via the
broadcast medium. Announcements are sent
over the network to associate triggers with
content streams. An announcement describes
the content, and may include information
regarding bandwidth, storage requirements,
and language.
Deliver y Protocols
For traditional bi-directional Internet communication,
the Hypertext Transfer Protocol
(HTTP) defines how data is transferred at the
application level. For uni-directional broadcasts
where a two-way connection is not available,
ATVEF also defines a uni-directional
application-level protocol for data delivery:
Uni-directional Hypertext Transfer Protocol
(UHTTP).
Like HTTP, UHTTP uses traditional URL
naming schemes to reference content. Content
can reference enhancement pages using the
standard “http:” and “ftp:” naming schemes.
However, ATVEF also adds the “lid:,” or local
identifier URL, naming scheme. This allows
reference to content that exists locally (such as
on the receiver's hard drive) as opposed to on
the Internet or other network.
Bindings
How data is delivered over a specific network
is called binding. The ATVEF has defined bindings
for IP multicast and NTSC. The binding to
IP is referred to as “reference binding”.
ATVEF Over NTSC
Transport Type A triggers are broadcast on
data channel 2 of the EIA-608 captioning signal.
Transport Type B binding also includes a
mechanism for delivering IP over the vertical
blanking interval (VBI), otherwise knows as
IP over VBI (IP/VBI). At the lowest level, the
television signal transports NABTS (North
American Basic Teletext Standard) packets
during the VBI. These NABTS packets are
recovered to form a sequential data stream
(encapsulated in a SLIP-like protocol) that is
unframed to produce IP packets.
“Raw” VBI Data
“Raw”, or oversampled, VBI data is simply digitized
VBI data. It is typically oversampled
using a 2× video sample clock, such as 27
MHz. Two applications for “raw” VBI data are
PCs (for software decoding of VBI data) and
settop boxes (to pass the VBI data on to the
NTSC/PAL encoder).
VBI data may be present on any scan line,
except during the serration and equalization
intervals.
One requirement for oversampled VBI
data is that the “active line time” be a constant,
independent of the horizontal timing of the
BLANK* control signal. Thus, all the VBI data
is assured to be captured regardless of the output
resolution of the active video data.
A separate control signal, called
VBIVALID*, may be used to indicate when VBI
data is present on the digital video interface.
This simplifies the design of graphics chips,
NTSC/PAL encoders, and ASICs that are
required to separate the VBI data from the digital
video data.

“Sliced” VBI Data
“Sliced”, orbinary,VBIdataisusefulinMPEG
video systems, such as settop boxes, DVD, digital
VCRs, and TVs. It may also be used in PC
applications to reduce PCI bandwidth.
VBI data may be present on any scan line,
except during the serration and equalization
intervals.
A separate control signal, called
VBIVALID*, may be used to indicate when VBI
data is present on the digital video interface.
This simplifies the design of graphics chips,
NTSC/PAL encoders, and ASICs that are
required to separate the VBI data from the digital
video data.
NTSC/PAL Decoder Considerations
For sliced VBI data capture, hysteresis must
be used to prevent VBI decoders from rapidly
turning on and off due to noise and transmission
errors. In addition, the VBI decoders
must also compensate for DC offsets, amplitude
variations, ghosting, and timing variations.
For closed captioning, the caption VBI
decoder monitors the appropriate scan lines
looking for the clock run-in and start bits used
by captioning. If found, it locks on to the clock
run-in, the caption data is sampled, converted
to binary data, and the 16 bits of data are transferred
to registers to be output via the host
processor or video interface. If the clock run-in
and start bits are not found, it is assumed the
scan line contains video data, unless other VBI
data is detected.
For WSS, the WSS VBI decoder monitors
the appropriate scan lines looking for the runin
and start codes used by WSS. If found, it
locks on to the run-in code, the WSS data is
sampled, converted to binary data, and the 14
or 20 bits of data are transferred to registers to
VBI Data 371
be output via the host processor or video interface.
If the clock run-in and start codes are not
found, it is assumed the scan line contains
video data, unless other VBI data is detected.
For teletext, the teletext VBI decoder monitors
each scan line looking for the 16-bit clock
run-in code used by teletext. If found, it locks
on to the clock run-in code, the teletext data is
sampled, converted to binary data, and the
data is then transferred to registers to be output
via the teletext or video interface. Conventional
host serial interfaces, such as I 2 C,
cannot handle the high bit rates of teletext.
Thus, a 2-pin serial teletext interface is commonly
used. If the 16-bit clock run-in code is
not found, it is assumed the scan line contains
video data, unless other VBI data is detected.
Ghost Cancellation
Ghost cancellation is required due to the high
data rate of some services, such as teletext.
Ghosting greater than 100 ns and –12 dB corrupts
teletext data. Ghosting greater than –3
dB is difficult to remove cost-effectively in
hardware or software, while ghosting less than
–12 dB need not be removed. Ghost cancellation
for VBI data is not as complex as ghost
cancellation for active video.
Unfortunately, the GCR (ghost cancellation
reference) signal is not commonly used in
many countries. Thus, a ghost cancellation
algorithm must determine the amount of
ghosting using other available signals, such as
the serration and equalization pulses.
NTSC Ghost Cancellation
The NTSC GCR signal is specified in ATSC A/
49 and ITU-R BT.1124. If present, it occupies
lines 19 and 282. The GCR permits the detection
of ghosting from –3 to +45 µs, and follows
an 8-field sequence.

372 Chapter 8: NTSC, PAL, and SECAM Overview
PAL Ghost Cancellation
The PAL GCR signal is also specified in
BT.1124 and ETSI ETS 300732. If present, it
occupies line 318. The GCR permits the detection
of ghosting from –3 to +45 µs, and follows
a4-framesequence.
References
1. Advanced Television Enhancement
Forum, Enhanced Content Specification,
1999.
2. ANSI/SMPTE 12M–1999, Television,
Audio and Film—Time and Control Code.
3. ANSI/SMPTE 170M–1999, Television—
Composite Analog Video Signal—NTSC for
Studio Applications.
4. ANSI/SMPTE 262M–1995, Television,
Audio and Film—Binary Groups of Time
and Control Codes—Storage and Transmission
of Data.
5. ANSI/SMPTE 309M–1999, Television—
Transmission of Date and Time Zone Information
in Binary Groups of Time and Control
Code.
6. ATSC A/49, 13 May 1993, Ghost Cancelling
Reference Signal for NTSC.
7. BBC Technical Requirements for Digital
Television Services, Version 1.0, February
3, 1999, BBC Broadcast.
8. EIA-189-A, July 1976, Encoded Color Bar
Signal.
9. EIA–516, May 1988, North American Basic
Teletext Specification (NABTS).
10. EIA–608, September 1994, Recommended
Practice for Line 21 Data Service.
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